A 0.0795-g sample of magnesium metal reacts with hydrochloric acid to give 88.5 mL of hydrogen gas at 25 degree C and 766 mm Hg. Required:
a. Calculate the moles of hydrogen gas produced.
b. Calculate the molar volume of hydrogen gas at STP.
c. What are major sources of experimental error?

(a). 0.0037 mol.

(b). 22.42 L

(c). => When the measuring apparatus are not precise.

=> Error due to parallax.

=> Random errors.

Explanation:

Without mincing words let us dive straight into the solution to the question above. So, we are given the following parameters or information which are going to aid in solving this particular Question;

Mass of magnesium given= 0.0795 g, volume of Hydrogen = 88.5 mL = 0.0885 L, temperature = 25 degree C = 273 + 25 = 298K and pressure = 766 mm Hg = 766/760 = 1.00789 atm.

(a). In order to determine the number of moles of Hydrogen atoms,we will be making use of the formula below;

Number of moles = (pressure × Volume)/ gas constant,R × Temperature.

Thus,the number of moles of Hydrogen = 1.00789 × 0.0885 / [( 0.08206 × 298] = 0.0037 mol.

(b). The molar volume at stp can be calculated by using the same formula that was used in (a) above;

Molar Volume at stp = Gas constant,R × temperature/ Pressure = 0.08206 × 273 / 1 atm = 22.42 L.

(c). The major sources of errors are given below:

=> When the measuring apparatus are not precise.

=> Error due to parallax.

=> Random errors.