Question

Excess hydrochloric acid is reacted with a sample of potassium carbonate. After drying, the potassium chloride weighs 4.62 g. What is the volume of carbon dioxide gas produced if the reaction occurs at 18°C and 741 mmHg?

K2CO3(s) + 2HCl(aq) → 2KCl(aq) + H2O(l) + CO2(g)

0.381 L

0.192 L

1.52 L

0.757 L

Answer 1

Molar mass of KCl = 1*MM(K) + 1*MM(Cl)

= 1*39.1 + 1*35.45

= 74.55 g/mol

mass of KCl = 4.62 g

mol of KCl = (mass)/(molar mass)

= 4.62/74.55

= 0.0620 mol

From balanced chemical reaction, we see that

when 2 mol of KCl forms, 1 mol of CO2 is formed

mol of CO2 formed = (1/2)* moles of KCl

= (1/2)*0.0620

= 0.0310 mol

we have:

P = 741.0 mm Hg

= (741.0/760) atm

= 0.975 atm

n = 0.0310 mol

T = 18.0 oC

= (18.0+273) K

= 291 K

we have below equation to be used:

P * V = n*R*T

0.975 atm * V = 0.031 mol* 0.08206 atm.L/mol.K * 291 K

V = 0.759 L

Answer: 0.757 L