Specific heat of Magnesium is 1.02 J/g K. Specific heat, or specific heat capacity, is a property related to internal energy that is very important in thermodynamics. Planning A: Refer to lab handout entitled, Heat of Reaction for the Formation of Magnesium Oxide. qB=2350 J = 2.350 kJ. 1.3.1 Specific heat capacity. The specific heat of magnesium: Heat capacity is the quantity of heat absorbed (emitted) whole body in the process of heating (cooling) by 1 Kelvin. Electrostatic capacitors can enable ultrafast energy storage and release, but advances in energy density and efficiency need to be made. Tossups . Planning B: Refer to lab handout entitled, of Reaction for the Formation of Magnesium Oxide. This paper. What Is Magnesium Oxide Used For?Regulates Magnesium Levels. Magnesium deficiency has a number of contributing factors including diet, food allergies, alcoholism, and poor kidney health.Manages Gastrointestinal Problems. Relieves Depression. Reduces Blood Pressure and Risk of Stroke. Reduces Migraines. Lowers Colorectal Cancer Risk. graduated cylinders, 150 mL beaker, aluminum slug, magnesium ribbon, magnesium oxide, 1.00 M HCl, 1.00 M NaOH, copper wire. Latent Heat of Vaporization of Magnesium is 127.4 kJ/mol. Specific Heat Capacity of Materials Specific heat, or specific heat capacity, is a property related to internal energy that is very important in thermodynamics. 4.7 kJ/g.C. To determine the accuracy of the calculation we can determine the % error: As far as accuracy goes a percent error of 2.75% is very acceptable. Planning B: Refer to lab handout entitled, of Reaction for the Formation of Magnesium Oxide. Dieter Haemmerich, in Principles and Technologies for Electromagnetic Energy Based Therapies, 2022. The specific heat capacity c [J/(kg K)] of tissue describes how much energy is required to change the temperature of 1 kg of tissue by 1 K (=1C). qB= (101.76 g + 0.158 g) x 4.184 J/gC x 5.50C. It occurs in nature as the mineral brucite. See also tabulated values for gases, food and foodstuff, metals and semimetals, common liquids and fluids and common solids, as well as values of molar specific heat for common organic substances and inorganic substances. As mentioned earlier, aluminum metal has about a 4 nanometer thick aluminum oxide layer on its surface. K). Magnesium oxide and other magnesium compounds are also used in the agricultural, chemical, and construction industries. The specimens were heated in a vertical carbon tube furnace with a magnesite tube liner for oxidizing conditions. Cobalt oxide has a thermal diffusivity minimum and a thermal conductivity maximum at 287 K as well as a specific heat capacity maximum as results of the magnetic transition. In this study, we report a novel method to synthesize nanofluids by dissolving magnesium metal in NaClCaCl 2 eutectic molten salt to enhance the specific heat capacity without the conventional agglomerate effect of nanoparticles. Units of Heat - BTU, Calorie and Joule - The most common units of heat BTU - British Thermal Unit, Calorie and Joule. Here, by doping equimolar Zr, Hf and Sn into Bi 4 Specific Heat. The heat capacity of single crystals of magnesiuim oxide has been measured in the tempera- ture range 3 to 270 'K with estimated accuracies of + 0 5 % for 10 < T < 20 'K and + 0 2 % for T> 20 'K. K) For example, when infused with silicon carbide nanoparticles, it has extremely high specific strength. Enthalpy of Formation of Magnesium Oxide Adapted with permission from the United States Air Force Academy. The specific heat (= specific heat capacity) at constant pressure and constant volume processes, and the ratio of specific heats and individual gas constants - R - for some commonly used "ideal gases", are in the table below (approximate values at 68 o F (20 o C) and 14.7 psia (1 atm)).. For conversion of units, use the Specific heat online unit converter. Latent Heat of Vaporization of Magnesium is 127.4 kJ/mol. Accordingly, it was found that high capacity may be achieved using the composite positive electrode active material of Magnesium Hydroxide. It is a measure of a substances ability to transfer heat through a material by conduction. Magnesium is used in super-strong, lightweight materials and alloys. Considerations regarding specific PPE 221 10.3. Substituting Eq 8 The average grain size is 25 mm, measured by optical microscopy of a fracture surface. The mean specific heat of pure aluminum and magnesium oxides has been determined from room temperature up to 1700C and 1800C, respectively. Beryllium hydroxide; Magnesium hydroxide is the inorganic compound with the chemical formula Mg(OH) 2. The latter is obtained by the treatment of magnesium chloride MgCl 2 solutions, typically seawater, with limewater or milk of lime. We measured three different thicknesses of speci-mens in order to determine whether our method for simultaneously determining thermal conductivity k and specific interfacial thermal resistance RT would be valid. 14.644 W/m*K. Thermal Diffusivity of Stainless Steel. These values agree well with the reported one; 17.6 cal/molK, i.e. Use this link for bookmarking this species for future reference. Reactions of chlorine, bromine and iodine with aluminium specific heat capacity and thermal conductivity in this demonstration. Thermal Properties. What is claimed is: 1. Powder Specific Surface Area, M2/g Activity in Neoprene Description Stan-Mag 112 28 49.0 Low Calcined MgO Stan-Mag MLW 95 125 High Calcined MgO The chemical formula is Mg (OH)2, where the magnesium particles are positively charged, and the OH particlescalled hydroxide groupsare negatively charged. Determine the H rxn, the enthalpy of reaction, in kJ/mol for several different Magnesium oxide (1011) MgO - about 1.0 g needed 5. Download Full PDF Package. Specific heats allow the heat absorbing capabilities of different substances to be compared. number 1309-48-4 Chemical formula MgO Formula weight 40.31 Assay Not less than 96.0% after ignition at about 800o DESCRIPTION Very bulky white powder, known as light magnesium oxide, or as a relatively dense, white powder, known as heavy magnesium oxide. Water - Specific Heat vs. Since the valency of magnesium is two, then the magnesium oxide contains one atom of oxygen and one atom of magnesium. Magnesium hydroxide is an inorganic salt, which means it's not carbon based like the molecules of life, and it's made up of positively and negatively charged particles. If you have problems with the units, feel free to use our temperature conversion or Aluminium Oxide (Al2O3) or alumina is one of the most versatile of refractory ceramic oxides and finds use in a wide range of applications. K). sorbents of the invention can reduce the sulfur Specific heat of Magnesium is 1.02 J/g K. Latent Heat of Fusion of Magnesium is 8.954 kJ/mol. 05.10.2019 29.10.2020 Robosup Indestructible alloy of titanium and tantalum. Specific heat of sodium. This is the typical heat capacity of water. The specific heat for water is 4.184 J/(gC), however when solutes are dissolved in it the specific heat changes. Related Resources: materials Specific Heat Capacity of Metals Table Chart. 5 g of Of great value to design and operations engineers, it gives practical process and equipment design descriptions, basic data, plant performance results, and other detailed information on gas purification Heat magnesium and sand together to produce silicon by an exothermic reaction. Download PDF. above are different versions of the heat capacity of the object. Widely used as high temperature and heat resistant materials. Specific, in physics, often means per unit mass, so specific heat capacity is the heat energy (usually in joules) required to raise a fixed mass of substance (usually one kilogram) by one unit of temperature. The heat of fusion for pure magnesium is 0.370 0.015 MJ/kg (159.076.45 BTU/lb). The specific heat capacity of the solution in this experiment is approximately 4.07 J g-1 C-1 and its density (1.01 g/cm 3 ) 1 , which is required to calculate the heat evolved. 21.09.2019 25.10.2020 Robosup. The active material includes orthorhombic system oxide represented by the following formula: Li x M1M2 2 O 6. June 28, 2021. For the NaOH and HCl reaction, the specific heat of the solution, c, is 4.025 J/(gC) while for the Mg and MgO reactions with HCl, c is equal to 3.862 J/(gC). Specific Heat Capacity of Metals Table Chart . Magnesium oxide is produced by the calcination of magnesium carbonate or magnesium hydroxide. MAGNESIUM OXIDE LEARNING OBJECTIVES To use a simple coffee-cup calorimeter to determine the enthalpy of formation of magnesium oxide. Using these terms we obtain: - n o Hrxn = CcalT + (m)(c)(T) where: It has a melting point of 650 centigrade, which is similar to that of aluminum. Start Over. * ~ iN > Si SN a a? By continuing to browse this site you agree to our use of cookies. Specific heat capacity (J kg 1 K 1) Specific heat capacity is the amount of energy needed to change the temperature of a kilogram of a substance by 1 K. Young's modulus. An antibody comprising a variable domain, said variable domain comprising at least 95% amino acid sequence identity to an amino acid sequence selected from the group consisting of SEQ ID NO: 29, SEQ ID NOs: 15-28, and SEQ ID NOs: 30-52 or a fragment thereof. Reliable results were not obtained below 10K because of desorption of helium exchange gas in the calorimeter vessel. Maximum specific heat capacity determined is 1006 J/kgK at 286.8 K in the first run and 1000 J/kgK at 286.8 K in the second one. Magnesium is too reactive to occur in nature as an element, but its compounds are common. To employ Hesss Law in the determination. Citation in PubAg 220; Journal. A Bunsen ice calorimeter and the drop method Information on this page: Solid Phase Heat Capacity (Shomate Equation) References; Notes; Other data available: Gas phase thermochemistry data; Condensed phase thermochemistry data; Gas phase ion energetics data 1 shows that the GC sample has a broken structure and a smooth surface, while the surface of the AC modified with magnesium oxide became rougher, which is speculated to be magnesium oxide in light of some observed particles on the AC. Revised: 2013. Temperature - Online calculator, figures and tables showing specific heat of liquid water at constant volume or constant pressure at temperatures from 0 to 360 C (32-700 F) - SI and Imperial units. 2. See also tabulated values for gases, food and foodstuff, metals and semimetals, common liquids and fluids and common solids, as well as values of molar specific heat for common organic substances and inorganic substances. Measurements of the heat capacity of pure magnesium and ultralight magnesiumlithium alloy with a Li content of 30 at. Data Collection: Quantitative Table I: Compound Trial Mass0.001g Volume of HCl0.5mL Temperature of HCl0.5C Time (seconds) Temperature of solution0.5C MgO 1 1.020 100.0 Application areas: High purity magnesium oxide has excellent alkali resistance and electrical insulation at high temperatures. Pascal Richet. * Exposure to Magnesium Oxide can cause metal fume fever. This is a flu-like illness with symptoms of metallic Related Resources: materials Specific Heat Capacity of Metals Table Chart. 3.68 mm 2 /s. Our HEAVY MAGNESIUM OXIDE has an extremely high bulk density, much higher than that of other heavy magnesium oxides, which makes it an excellent filler. The specific heat of some commonly used solids is given in the table below.. For conversion of units, use the Specific heat online unit converter.. See also tabulated values of specific heat of gases, food and foodstuff, metals and semimetals, common liquids and fluids and other common substances as well as values of molar heat capacity of common organic substances and To determine the heat formation of MgO (Magnesium Oxide) using Hesss Law, which states the heat within a chemical reaction is independent of the pathway between the initial and final states. The average grain size is 25 mm, measured by optical microscopy of a fracture surface. Includes kit list and safety instructions. , the constant c s is the specific heat capacity (commonly called just specific heat). Wenieryesrenntdt Het RESEARCH LIBRARY Ore GebTY RESEARCH INSTITUTE JOHN MOORE ANDREAS COLOR CHEMISTRY LIBRARY FOUNDATION A SHORT MANUAL OF ANALYTICAL CHEMISTRY The heat capacity of single crystals of magnesium oxide has been measured in the temperature range 3 to 270K with estimated accuracies of 0.5% for 10 < T < 20K and 0.2% for T > 20K. Suboptimal or deficient magnesium status in subjects involved in strength training programmes may be associated with less efficient energy metabolism and impaired endurance capacity. Tech. , the constant c s is the specific heat capacity (commonly called just specific heat). With the assumption that the effect of anharmonicity of the lattice A short summary of this paper. Reliable results were not obtained below 10 'K because of desorption of How is molar heat capacity related to specific heat? Other names: Magnesium monoxide Permanent link for this species. Heat capacity (C) 77.03 Magnesium oxide: Other cations. Magnesium oxide functions by scavenging the chloride ions resulting from the cross-linking reaction. A measure of the stiffness of a substance. The mean specific heat of pure aluminum and magnesium oxides has been determined from room temperature up to 1700C and 1800C, respectively. qA= 9250 J = 9.250 kJ 9.253602176. qB= m (HCl+X)C xT. Latent Heat of Fusion: 1670: 1880: kJ/kg: 717.967: 808.25: BTU/lb: Maximum Service Temperature: 2250: 2400: K: 3590.33: 3860.33 F: Melting Point: 3080: 3135: K: 5084.33: 5183.33 F: Minimum Service Temperature: 0: 0: K-459.67-459.67 F: Specific Heat: 880: 1030: J/kg.K: 0.680995: 0.797074: BTU/lb.F: Thermal Conductivity: 30: 60: W/m.K: 56.161: 112.322: 5 However, heat released is equal to H: H = Q = (Cp) T Eq. Owing to the hazards of chemical and physical syntheses of magnesium oxide nanoparticles (MgO NPs), an eco-friendly, high-yield, and promising biological method is highly desirable for biomedical applications. 2022 Reinstein Set (VCU Version) Packet 1 . The heat capacity of single crystals of magnesium oxide has been measured in the temperature range 3 to 270K with estimated accuracies of 0.5% for 10 < T < 20K and 0.2% for T > 20K. The heat of the explosion determines the work capacity of an explosive. According to the textbook, the accepted value for HT=-601.8 kJ/mol. Magnesium hydroxide (milk of magnesia), sulfate (Epsom salts), chloride and citrate are all used in medicine. Characteristics. Properties. Specific heat is represented by c and is the heat capacity per gram. K) at 25 C) the second-highest among all the heteroatomic species (after ammonia), as well as a high heat of vaporization (40.65 kJ/mol or 2257 kJ/kg at the normal boiling point), both of which are a result of the extensive hydrogen bonding between its molecules. High thermal expansion coefficient and thermal conductivity have good light transmittance. A)Iron metal and Chlorine gas react to form solid iron(III) chloride. retical density of magnesium oxide [7]. Magnesium hydroxide (milk of magnesia), sulfate (Epsom salts), chloride and citrate are all used in medicine. Cover the crucible and heat strongly for approximately 5-10 minutes. Specific heat of Magnesium is 1.02 J/g K. Latent Heat of Fusion of Magnesium is 8.954 kJ/mol. Magnesium oxide is an inorganic substance of white color. The standard SI unit is Heat of Fusion: The specific heat of fusion if only slightly affected by alloying meaning that the values for alloys and pure magnesium are close. Physical Science. Specific Heat Capacity of Stainless Steel. Specific Heat for some common products are given in the table below. retical density of magnesium oxide [7]. Heat Capacity. What is the Specific heat capacity of magnesium nitrate hexahydrate? gas desulfurization sorbents and methods using them for removal of sulfur from gas streams, particularly at high temperatures ranging from 500 to 1000 C. The sorbents and methods are of particular application to produce a sulfur-clean feed from reformate gas generated from readily available transportation fuels containing sulfur. Engineering Materials. 1. Geochimica et Cosmochimica Acta, 1993. 983 J/kgK, at 287.3 K (King, 1957). Magnesium oxide is used to make heat-resistant bricks for fireplaces and furnaces. * Breathing Magnesium Oxide can irritate the eyes and nose. Toggle facets Limit your search Text Availability. Specific Heat Specific heat, or specific heat capacity, is a property related to internal energy that is very important in thermodynamics. In this formula, 0x5, M1 is at least one selected from the group consisting of Fe and Mn, and M2 is at least one selected from the group consisting of Nb, Ta and v. PTO PTO PDF Espace: Google: link PDF PAIR: Patent. A porous reduced silica fiber having a diameter of about 0.1 to about 20 microns, a surface area of about 5 m 2 /g to about 400 m 2 /g, and a porosity of about 0.01 cm 3 /g to about 1.5 cm 3 /g, wherein the porous reduced silica fiber comprises SiO x where x=0-2; and wherein the porous reduced silica fiber comprises greater than about 20 weight graduated cylinders, 150 mL beaker, aluminum slug, magnesium ribbon, magnesium oxide, 1.00 M HCl, 1.00 M NaOH, copper wire. 2. Turn off the Bunsen burner and when safely cooled, weight the entire ceramic crucible containing the Magnesium with the lid on; record the value . Fig. Engineering Materials. Common Name: MAGNESIUM OXIDE CAS Number: 1309-48-4 DOT Number: None DOT Hazard Class: None ----- HAZARD SUMMARY * Magnesium Oxide can affect you when breathed in. We measured three different thicknesses of speci-mens in order to determine whether our method for simultaneously determining thermal conductivity k and specific interfacial thermal resistance RT would be valid. C)Solid magnesium reacts with aqueous . Unknown A-xxxx (1012) in your unknown packet - need at least 2-3 grams The specific heat of Chemical names Magnesium oxide C.A.S. Thermal Conductivity of Stainless Steel. above are different versions of the heat capacity of the object. 37 Full PDFs related to this paper. When aluminum and magnesium are used as the shell in an encapsulated heat sink, they can have very high specific thermal conductivity values. Although magnesium is not quite as good of a thermal conductor as aluminum, its low density makes it a perfect material for applications that are weight-sensitive. experiment are assumed to have a heat capacity, (Cp, aq), of 0.00418 kJ/mLKelvin (that is, 4.18 Joules are needed to raise the temperature of 1 mL of solution 1K). The specific heat capacity of water is 4.184 J C-1g. Our HEAVY MAGNESIUM OXIDE has a bulk density around 1 g/mL when standard heavy magnesium oxides are close to 0.25 g/l. This countrys 1963 revolution is sometimes called the Ramadan Revolution and was followed by Ali Salih al-Sadis National Guard killing suspected dissidents. magnesium oxide specific heat capacity. Reliable results were not obtained below 10K because of desorption of helium exchange gas in the calorimeter vessel. The intensive properties c v and c p are defined for pure, simple compressible substances as partial derivatives of the internal energy u(T, v) and enthalpy h(T, p) , respectively: This layer is about 0.004% the thickness of a piece of paper! The XRD results indicated that all coatings consist of MgO and MgF2 , while specific products such as Mg2 SiO4 , MgSiO3 , Mg2 P2 O7 , and MgAl2 O4 were also present in specimens based on the selected solution. Enthalpy and heat capacity of magnesium oxide and zirconium oxide in the temperature range 1200 to 2500$sup 0$K. On the other hand, the combination of lower heat capacity and heat of fusion of magnesium means that less energy is consumed during welding and offers the potential to achieve higher welding speeds. In a few cases, the respiratory rate is recorded to plummet along with the blood pressure.It also has an effect on the cardiovascular system, and may br a proven agent in causing a decreased myocardial vasodilation, hypertension, and bradyarrhythmias.Magnesium oxide can also cause suppression of the release of Parathyroid Hormone (PTH).More items Specific heat capacity (J kg 1 K 1) Find the heat capacity (Cp) of a calorimeter and contents (calibration). The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or ), measured in W/m.K. It is also added to cattle feed and fertilisers. Specific heat is a physical quantity, numerically equal to the quantity of heat which must be transferred to a body with mass of 1 kg in order that its temperature has changed by 1 Kelvin. Magnesium is the lightest of all metals, being about two-thirds lighter than aluminium. B)Solid aluminum carbonate decomposes to form solid aluminum oxide and carbon dioxide gas. Thermal Properties of Stainless Stainless Steel 304 . Read Paper. The specimens were heated in a vertical carbon tube furnace with a magnesite tube liner for oxidizing conditions. The Fig. As shown in Table 1 above, the composite positive electrode active material UT-CO 2 Co of Example 1 had increased I(003)/I(104) compared to the positive electrode active material of Comparative Example 4, consistent with a reduced cation mixing ratio. total heat capacity of the system at constant pressure, Cp: Q = (Cp) T Eq. The specific heat is the amount of heat energy per unit mass required to raise the temperature by one degree Celsius.The relationship between heat and temperature change is usually expressed in the form shown below where c 3. beryllium (Be), formerly (until 1957) glucinium, chemical element, the lightest member of the alkaline-earth metals of Group 2 (IIa) of the periodic table, used in metallurgy as a hardening agent and in many outer space and nuclear applications. We use cookies to enhance your experience. Specific Heat Capacity J/(gk) Youngs Modulus Gpa Thermal Conductivity W/(mK) Coeffiecient of Linear Expansion x 10-6/K Melting Temp (C) Molar Mass (g/mol) Magnesium Diboride (MgB 2) 2.57 1.05 - 10-70 8 800 45.93 Titanium Diboride (TiB 2) 4.52 0.63 370-570 60-120 5.6-10 2970 69.49 Zirconium Di-boride (ZrB 2) 6.09 0.42 344-440 23 5.2-6.7 3246 112.84 Heat capacity of magnesium aluminosilicate melts. As a step in developing new standards of high-temperature heat capacity and in deter mining accurate thermodynamic data for simple substances, the enthalpy (heat content) relative to 273 K, of high purity fused magnesium oxide, MgO, and of sintered beryllium oxide, BeO, was measured up to 1,173 K. magnesium oxide specific heat capacity. Magnesium Properties and uses: Magnesium is a very useful metal both as a pure metal and in alloys its main properties are as follows: 1. atomic number 4 atomic weight 9.0121831 melting point 1,287 C (2,349 F) boiling point 2,471 C (4,480 F) specific gravity 1.85 at 20 C The intensive properties c v and c p are defined for pure, simple compressible substances as partial derivatives of the internal energy u(T, v) and enthalpy h(T, p) , respectively: Specific Heat Capacity of Metals Table Chart . Specific Heat for some common products are given in the table below. Values of thermal conductivities for the above five materials were calculated from the measured thermal diffusivity values and specific heat capacity values. It is very light with a specific gravity of 1.74. The specific heat is the amount of heat energy per unit mass required to raise the temperature by one degree Celsius.The relationship between heat and temperature change is usually expressed in the form shown below where c Therefore the heat formation of MgO was determined to be -618.35 kJ/mol. Planning A: Refer to lab handout entitled, Heat of Reaction for the Formation of Magnesium Oxide. Specific Heat Capacity of Metals Table Chart . such as heat-resistant, high-temperature insulating materials and can be prepared from economical precursors [1]. (in Russian) This massively updated and expanded fifth edition is the most complete, authoritative engineering treatment of the dehydration and gas purification processes used in industry today. It is also added to cattle feed and fertilisers. You searched for: Publication Year 2022 Remove constraint Publication Year: 2022 Subject aluminum oxide Remove constraint Subject: aluminum oxide. The heat capacity of the solution is given by the specific heat of the solution, C s, multiplied by the mass of the solution: Csoln = C s * mass of the solution (8) The specific heat of 0.4 M HCl, which is the average molarity of the acid used during todays reaction, is 4.07 J g-1 C-1 and its density is 1.01 g/cm3. Magnesium oxide is used to make heat-resistant bricks for fireplaces and furnaces. 1(A, a) and (B, b) show that a large number of magnesium oxide particles agglomerate on the surface of the 10MgO/C-P Includes kit list and safety instructions. Categories. The mean specific heat of pure aluminum and magnesium oxides has been determined from room temperature up to 1700C and 1800C, respectively. Magnesium is non-toxic, non-magnetic, has high-impact strength and is resistant to denting. The heat capacity of the calorimeter must be measured in a separate experiment. It is a white solid with low solubility in water (K sp = 5.6110 12). Heat capacity of magnesium aluminosilicate melts. 7631 Ws 0.5 / (m 2 K) Heat of Formation of Magnesium Oxide Objetive To determine the heat formation of MgO (Magnesium Oxide) using Hesss Law, which states the heat within a chemical reaction is independent of the pathway between the initial and final states. 1. ACS applied materials & interfaces 16; Colloids and surfaces 14; Specific heat capacity (J kg 1 K 1) (II) oxide and zinc in this class demonstration. immediately or shortly after exposure to Magnesium Oxide: * Breathing Magnesium Oxide can irritate the eyes and nose. * Exposure to Magnesium Oxide can cause metal fume fever. This is a flu-like illness with symptoms of metallic taste in the mouth, headache, fever and chills, aches, chest tightness and cough. The symptoms may be delayed for Philippe Courtial. The application of Magnesium oxide: High purity magnesium oxide. 9698422. 502 J/kg*K. Thermal Effusivity of Stainless Steel. Specific Heat Specific heat, or specific heat capacity, is a property related to internal energy that is very important in thermodynamics. Data Collection: Quantitative Table I: Compound Trial Mass0.001g Volume of HCl0.5mL Temperature of HCl0.5C Time (seconds) Temperature of solution0.5C MgO 1 1.020 100.0 To then calculate the heat formation of MgO HT, the sum of all the reactions must be determined including HC, the heat formation of water, which is already predetermined to be -285.8 kJ/mol.
