Question 6 of 8 > Calculate the standard enthalpy change for the reaction at 25 °C. Standard enthalpy of formation values can be found in this
list of thermodynamic properties.
H2O(g) + C(graphite)(s)
H2(g) + CO(g)
KJ
ΔΗΓκη
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Q
5:24 PM
8/2/2020

131.29 kJ

Explanation:

Let's consider the following balanced equation.

H₂O(g) + C(graphite)(s)  ⇄ H₂(g) + CO(g)

Given the standard enthalpies of formation (ΔH°f), we can calculate the standard enthalpy change for the reaction (ΔH°r) using the following expression.

ΔH°r = 1 mol × ΔH°f(H₂(g)) + 1 mol × ΔH°f(CO(g)) - 1 mol × ΔH°f(H₂O(g)) - 1 mol × ΔH°f(C(graphite)(s))

ΔH°r = 1 mol × (0 kJ/mol) + 1 mol × (-110.53 kJ/mol) - 1 mol × (-241.82 kJ/mol) - 1 mol × (0 kJ/mol)

ΔH°r = 131.29 kJ

h

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.