Question

Fill in the Blanks Given this balanced chemical reaction, 4 HCl(g) + O2(g) +2H20(0) + 2 C12(e) AH reaction=-202.4 kJ (give answer in decimal notation, i.e. 234,000) a. How many J (joules) of heat are released when 2.50 moles of HCl react with excess oxygen gas? b. How many moles of HCl are there in 89.3 g of HCl? c. How many kJ of heat are released when 89.3 g of HC react with excess O2? (Enter your answers as numbers not words.)

Answer 1

a)
From reaction,
When 4 moles of HCl reacts, heat released = 202.4 KJ
So,
When 2.50 moles of HCl reacts, heat released = 202.4*2.50/4
= 126.5 KJ
= 126500 J

Answer: 126500 J

b)

Molar mass of HCl,
MM = 1*MM(H) + 1*MM(Cl)
= 1*1.008 + 1*35.45
= 36.458 g/mol


mass(HCl)= 89.3 g

use:
number of mol of HCl,
n = mass of HCl/molar mass of HCl
=(89.3 g)/(36.46 g/mol)
= 2.449 mol
Answer: 2.45 mol

c)
Since Δ H is negative, heat is released
when 4 mol of HCl reacts, heat released = 202.4 KJ
So,
for 2.449 mol of HCl, heat released = 2.449*202.4/4 KJ
= 1.239*10^2 KJ
Answer: 124 KJ