0.0075 mole of calcium trioxocarbonate (IV) is added to 0.015 mole of a solution of hydrochloric acid. The volume of gas evolved at s.t.p is?
[Molar volume of a gas at s.t.p = 22.4 dm3]
A
224cm3
B
168cm3
C
112cm3
D
100cm3
Verified Correct Answer: B.
Step-by-Step Mathematical Solution
1mole of gas at STP = 22.4dm\(^3\)
0.0075 mole of CaCO3 = xdm\(^3\)
cross multiply;
where 22.4dm\(^3\) = 22400cm\(^3\)
x * 1 = 0.0075 * 22400 → 168cm\(^3\)
the gas CO2 which evolved was gotten from CaCO3 so we use the number of moles of CaCO3 only
Source: WAEC / JAMB / NECO Classroom Archive (Record #4291)