🧪 MRCHEMCOACH DIGITAL LAB

IGCSE Experiment: Rate of Reaction (Acid and Metal)

Score: 0/19

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Conical Flask

Please select an acid concentration above to begin.

Theory & Details

Reaction Equation:

Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

Objective: Investigate how changing the concentration of acid affects the rate of chemical reaction.

Method: Add 30 cm³ of hydrochloric acid to the flask, drop in the magnesium ribbon, and time how long it takes for the solid to completely dissolve.

Exp	Acid	Conc (M)	Time (s)

Part B: Graph: Concentration vs Time

Part C: Interpolation

Use your graph to estimate the reaction time at a concentration of 1.3 mol dm⁻³.

Estimated Time at 1.3 M:

Solution: The estimated time should be approximately 34 seconds. (Acceptable range usually between 30s to 38s depending on your specific curve of best fit).

Part D: Rate of Reaction Calculations

Calculate the average rate of reaction for Acid A using the formula: Rate = 5 cm ÷ time

Based on your results, which acid produced the slowest rate of reaction?

Solution:
1. Rate for Acid A = 5 ÷ (Time recorded for Acid A). Make sure to include units (cm/s or cm s⁻¹).
2. The slowest rate of reaction is produced by Acid E (0.5 M) because the lower concentration means fewer collisions per second, hence taking the longest time to dissolve the ribbon.

Part E: Experimental Evaluation

Explain why it is a good experimental practice to repeat the experiment for each concentration.

Solution: Repeating an experiment is crucial because it allows you to spot any anomalous (random error) results. You can then calculate a mean average (excluding anomalies), making your final data and conclusion much more reliable.

Part F: Temperature Control Investigation

Initial Temp (°C)	Final Temp (°C)	Change (ΔT)

Why is it important to keep the temperature constant when investigating the effect of concentration? Suggest a method to do this.

Solution: Temperature also affects the rate of reaction. If temperature is not controlled, it will not be a fair test, and you cannot be certain if a change in rate was caused by the concentration or the temperature change. You can control temperature by placing the reaction flask in a thermostatically controlled water bath.

Teacher Dashboard & Overview

Completion

Accuracy

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Graphing

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Calculations

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Total Score