It’s protons+neutrons+electrons that equal atomic mass
Answer: 209.2
Explanation:
4. q = mcat
q = 5g(4.184)(40-50)
q = -209.2
the negative sign indicates that heat is given off
Answer:
[NH₃] → 3.24 M
Explanation:
Our solute: Ammonia
Our solvent: Water
Solution's mass = Mass of solute + Mass of solvent
Solution's mass = 15 g + 250 g = 265g
We use density to determine, the volume.
D = mass /volume → Volume = m / D → 265 g /0.974 g/mL = 272.07 mL.
We convert the mL to L → 272.07 mL . 1L /1000mL = 0.27207 L
To determine molarity we need the moles of solute in 1 L of solution.
Moles of solute are: 15g / 17g/mol = 0.882 moles
[NH₃] = 0.882mol /0.27207 L → 3.24 M
To determine the standard heat of reaction, ΔHrxn°, let's apply the Hess' Law.
ΔHrxn° = ∑(ν×ΔHf° of products) - ∑(ν×ΔHf° of reactants)
where
ν si the stoichiometric coefficient of the substances in the reaction
ΔHf° is the standard heat of formation
The ΔHf° for the substances are the following:
CH₃OH(l) = -238.4 kJ/mol
CH₄(g) = -74.7 kJ/mol
O₂(g) = 0 kJ/mol
ΔHrxn° = (1 mol×-74.7 kJ/mol) - ∑(1 mol×-238.4 kJ/mol)
ΔHrxn° = +163.7 kJ
