Rates Of Reaction 2 (Collecting Gas) - GCSE Science Required Practical

Summary

Mr. Mitchell's video from Mars for Science explores two methods for measuring the rate of a chemical reaction: using a measuring cylinder and a gas syringe. He demonstrates the reaction between magnesium and hydrochloric acid at two concentrations: 2 moles per decimeter cubed and 1 mole per decimeter cubed. The video shows how to accurately measure gas production every 10 seconds and discusses the importance of precision and potential sources of error in the experiment.

Takeaways

• 🧪 Mr. Mitchell introduces two methods for measuring the rate of a chemical reaction involving magnesium and hydrochloric acid.
• 📏 The first method uses a measuring cylinder to measure the volume of gas produced by the reaction.
• 🌡️ The second method employs a gas syringe to track the gas volume, providing an alternative to the measuring cylinder.
• 🔬 Two different concentrations of hydrochloric acid are compared: 2 moles per decimeter cubed and 1 mole per decimeter cubed.
• 💧 Hydrochloric acid is measured in a conical flask using a measuring cylinder and pipette to ensure accuracy.
• 🕒 The reaction is timed and the volume of gas produced is recorded every 10 seconds.
• 📊 A graph is used to compare the reaction rates, with time on the x-axis and gas volume on the y-axis.
• ⚖️ The reaction stops when all the magnesium has reacted, as it is the limiting reactant.
• 🔍 Potential sources of error are discussed, including timing inaccuracies and the imprecision of the measuring cylinder.
• 🔬 An inverted burette is suggested as a more precise tool for measuring gas volume, allowing for more accurate results.

Q & A

What are the two methods Mr. Mitchell demonstrates for measuring the rate of a chemical reaction?

Mr. Mitchell demonstrates using a measuring cylinder and a gas syringe as the two methods for measuring the rate of a chemical reaction.

Which reactants are used in the experiment to measure the rate of a chemical reaction?

The reactants used in the experiment are magnesium and hydrochloric acid.

What are the two different concentrations of hydrochloric acid that Mr. Mitchell compares?

Mr. Mitchell compares two moles per decimeter cubed (2 M) against one mole per decimeter cubed (1 M) concentrations of hydrochloric acid.

How does the concentration of hydrochloric acid affect the rate of reaction?

A higher concentration of hydrochloric acid, such as 2 M, results in a faster rate of reaction compared to a lower concentration like 1 M.

What is the purpose of inverting the measuring cylinder filled with water during the experiment?

Inverting the measuring cylinder filled with water is to displace the gas produced during the reaction, allowing for the measurement of gas volume.

Why is it important to keep the gas syringe dry during the experiment?

The gas syringe needs to be kept dry to prevent the plunge from getting stuck, which would hinder the measurement of gas produced.

How often should the volume of gas produced be measured during the experiment?

The volume of gas produced should be measured every 10 seconds during the experiment.

What is the significance of the steepness of the curve on the graph in relation to the rate of reaction?

A steeper curve on the graph indicates a faster rate of reaction, as it shows a greater volume of gas being produced in the same amount of time.

Why does the reaction stop even though there is an excess of hydrochloric acid?

The reaction stops when all of the magnesium, the limiting reactant, has reacted, regardless of the excess hydrochloric acid.

What are some sources of error mentioned in the script that could affect the accuracy of the experiment?

Sources of error include the difficulty of starting the timer, putting the bung in, and adding magnesium simultaneously, and the imprecision of the measuring cylinder which can only read every one centimeter cubed of gas collected.

Why might using an inverted burette be more precise than a measuring cylinder in this experiment?

An inverted burette is more precise because it allows for readings of every 0.1 centimeter cubed of gas collected, providing a greater degree of precision in the results.