A laboratory assistant needs to prepare 35.2 liters of hydrogen at 25.0°C and 101.3 kilopascals. This is the equation for the reaction: 2HCl + Ca → H2 + CaCl2 What volume of 2.3 M hydrochloric acid is required to produce this much gas? Use the ideal gas resource. A. 0.625 L B. 0.876 L C. 1.18 L D. 1.25 L

The answer is D. 1.25

Explanation:

Plato

Volume of hydrogen gas = 35.2L

Temperature of hydrogen gas = 25.0°C + 273 = 298 K

Pressure of hydrogen gas = 101.3 kPa = 1 atm

(Conversion factor 1 atm = 101.325 kPa)

Using the Ideal gas law,

PV = nRT

where P, V, n, R and T are pressure, volume, number of moles, universal gas constant and temperature respectively.

n = PV/RT

The number of moles of hydrogen gas,

n = 35.2 L x 1 atm / 0.0821 L. atm. mol⁻¹1. K⁻¹ x 298 K

n = 1.438 moles

2HCl + Ca → H₂ + CaCl₂

Based on the given balanced equation, 1 mole of H₂ is produced from two moles of HCl.

Since H₂ is 1.438 moles, HCl will be (1.438 x 2) moles or 2.876 moles

Given, Molarity of HCl = 2.3 M

Molarity = moles of solute / liter of the solution

Thus the volume of HCl is,

2.3 M = 2.876 moles / liter of the solution

V = 2.876 moles / 2.3 M

V = 1.25 L

Thus the volume of 2.3 M hydrochloric acid required to produce the given amount gas is 1.25 L.