Waec Model Questions Vol1 2021 Chemistry Question 1

Practice practical question 1 from the 2021 Waec Model Questions Vol1 Chemistry examination. This question covers Atomic Structure, Stoichiometry, Gas Laws, Experimental Errors .

Waec Model Questions Vol1 2021 Chemistry Practical
Topics: Atomic Structure Stoichiometry Gas Laws Experimental Errors
Question 1 WAEC_MODEL_QUESTIONS_VOL1 • 2021 • CHEMISTRY • practical

A clean dry piece of magnesium ribbon is weighed and then reacted with excess dilute hydrochloric acid in a conical flask. The hydrogen gas produced is collected over water. The data obtained are: - Mass of magnesium ribbon before the reaction: 0.150 g - Volume of hydrogen collected: 158.0 mL - Temperature of the gas: 298 K - Atmospheric pressure: 100 kPa - Vapour pressure of water at 298 K: 3.2 kPa Using the ideal‑gas equation, determine the relative atomic mass of magnesium. State the balanced chemical equation and discuss two possible sources of experimental error and how they would affect the result.

Question Parts

( a )
Write the balanced chemical equation for the reaction between magnesium and hydrochloric acid.
( b )
Calculate the number of moles of hydrogen gas collected, correcting for the vapour pressure of water.
( c )
From the stoichiometry of the reaction, determine the number of moles of magnesium that reacted.
( d )
Using the initial mass of magnesium, calculate its relative atomic mass.
( e )
State two possible sources of error in this experiment and explain qualitatively how each would affect the calculated atomic mass of magnesium.

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About This Question

This is Waec Model Questions Vol1 2021 Chemistry Question 1. It is one of the practical questions from the 2021 Waec Model Questions Vol1 Chemistry examination.

The question covers Atomic Structure, Stoichiometry, Gas Laws, Experimental Errors .

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