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The ideal gas law PV = n RT relates pressure 115 atm, volume V, temperature T, a

ID: 1059200 • Letter: T

Question

The ideal gas law PV = n RT relates pressure 115 atm, volume V, temperature T, and number of moles of a gas The gas constant R equals L middot atm/K middot mol). To determine which values of R to use, examine the units reported for the variables in this gas equation. Make sure that like units cancel. The equation can be rearranged as follows to solve for n n = PV/RT this equation is useful when with gaseous reactions because When heated, calcium carbonate decomposes to yield calcium oxide and carbon dioxide gas via the reaction What is the mass of calcium carbonate needed to produce 57.0 L of carbon dioxide at STP?

Explanation / Answer

Part A

CaCO3 ---------> CaO + CO2

From the stoichiometry of the reaction

one mole of CaCO3( 100g/mol) gives one mole of CO2 ( 44g/mol = 22.4 L at STP)

Thus the amount of CaCO3 that produces 57.0L of CO2 at STP is

=57x100/22.4 = 254.46 g

mass of CaCO3 required = 254.46 g

Part B

The balanced reaction is 2 C4H10 + 13O2 ---------> 8CO2 + 10 H2O

Thus 2 moles of butane (2x58g/mol) gives 8 moles of CO2 (8x 22.4 L at STP)

Hence 3.8 g of butane gives

= 3.8 x 8x 22.4 /(2 x 58)

= 5.870 L of CO2 at STP

We need to calculate the volume of CO2 at 1atm and 23 C by using the realtion

P1V1/T1 = P2 V2/T2

1atm x V/296K = 1 atm x 5.870L / 273K

Thus Volume of CO2 at 1 atm and 23 C = 6.365 L