The ideal gas law PV=nRT relates pressure P, volume V, temperature T, and number

Question

The ideal gas law

PV=nRT

relates pressure P, volume V, temperature T, and number of moles of a gas, n. The gas constant R equals 0.08206 L?atm/(K?mol) or 8.3145 J/(K?mol). The equation can be rearranged as follows to solve for n:

n=PV/RT

This equation is useful when dealing with gaseous reactions because stoichiometric calculations involve mole ratios.

Part A

When heated, calcium carbonate decomposes to yield calcium oxide and carbon dioxide gas via the reaction

CaCO3(s)?CaO(s)+CO2(g)

What is the mass of calcium carbonate needed to produce 79.0L of carbon dioxide at STP?

Part B

Butane, C4H10, is a component of natural gas that is used as fuel for cigarette lighters. The balanced equation of the complete combustion of butane is

2C4H10(g)+13O2(g)?8CO2(g)+10H2O(l)

At 1.00 atm and 23 ?C, what is the volume of carbon dioxide formed by the combustion of 2.60g of butane?

Explanation / Answer

PART A

Let No. of moles of CO2 = n

Then by ideal gas equation n = PV/RT = (1 * 79) / (0.08026 * 273.15) = 79 / 22.71 = 3.48 MOL

No. of moles of Calcium Carbonate required = 3.48 mol

Mass of 3.48 mol of Calcium Carbonate = 3.48 * 100 = 348g

Ans = 348g

PART - B

Molar mass of butane = 58g

No. of moles of Butane = 2.60 / 58 = 0.0448

1 mol of butane gives 4 moles of Carbon dioxide.

Thus, 0.0448 mol of butane will give = 0.0448 * 4 =0.1792 mol of Carbon dioxide.

Volume of 1 mol of Carbon dioxide at STP = 22.71 L

Volume of 0.1792 mol of Carbon dioxide at STP = 22.71 * 0.1792 = 4.060 L

Answer = 4.060 L

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