Fluorine gas and water vapor react to form hydrogen fluoride gas and oxygen. What volume of hydrogen fluoride would be produced by this reaction if 4.8 cm^3 of fluorine were consumed?

Question

Answer has a unit symbol, and is rounded to the correct number of significant digits.

Answer 1

2F₂ (g) + 2H₂O (g) ---> 4HF (g) + O₂ (g) ... balanced equation

Assuming STP (standard temperature and pressure) we know that 1 mole of and idea gas = 22.4 liters

4.8 cm³ F₂ x 1 L/1000 cm³ x 1 mol/22.4 L = 2.1x10^-4 moles of F₂

moles HF produced = 2.x10^-4 moles F₂ x 4 moles HF / 2 moles F₂ = 4.3x10^-4 moles

Volume of HF produced = 4.3x10^-4 moles x 22.4 L/mole = 0.0096 liters = 9.6 cm³

Done another way without using moles since it is at STP:

4.8 cm³ F2 x 4 cm³ HF / 2 cm³ F2 = 9.6 cm³ HF

Answer 2

1) Write the Chemical Reaction

F2 (g) + H2O (g) ----> HF (g) + O2 (g)

2) Balance the equation

2F2 (g) + 2H2O (g) ---> 4HF (g) + O2 (g)

3) Use stoichiometry

REMEMBER: 1 mole of any gas at standard temperature (T) and pressure(P) (T = 273 K and P= 1 atm) occupies a volume (V) of 22.4 L

*** Assuming the reaction took place in standard temperature and pressure as it is not stated otherwise

A) Use the periodic table to obtain the Atomic Mass or the Atomic Weight of Fluorine (F2)

Atomic Mass or Atomic Weight of F = 18.998 g F

Atomic Mass or Atomic Weight of F2 = 18.998 *2 = 37.996 g F2

B) Use the atomic mass and find the Molar Mass (MM) using our balanced equation and atomic mass

1 mol F2 = 37.996 g F2

4 moles of HF is balanced with our 2 moles of F2 in our equation

C) we are given 4.8 cm^3 but using our assumption of standard temperature and pressure we need to be in liters so we need to further use dimensional analysis to convert to the correct units

Conversion Factors

1 cm^3 = 1 mL

1000 mL = 1 L

D) Use dimensional analysis to solve

(4.8 cm^3 F2) x ( 1 mL / 1 cm^3) x ( 1 L / 1000 mL) x (1 mol F2/ 22.4 L) x (1 mol F2 / 37.996 g F2 ) x (4 mol HF / 2 moles F2) x ( 22.4L / 1 mol HF) * (1000 mL / 1 L) * ( 1 cm^3 / 1 mL) = V

V = 0.25266 cm^3

We are only given two significant figures in the problem so our answer must be so:

V of HF in this reaction is 0.25 cm^3