Rates Of Reaction 2 (Collecting Gas) - GCSE Science Required Practical
Summary
TLDRMr. 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.
Outlines
🔬 Measuring Chemical Reaction Rates
In this educational video, Mr. Mitchell introduces viewers to the process of measuring the rate of a chemical reaction, focusing on two methods: using a measuring cylinder and a gas syringe. He explains that the experiment involves a reaction between magnesium and hydrochloric acid, comparing two concentrations: 2 moles per decimeter cubed and 1 mole per decimeter cubed. The video demonstrates how to accurately measure and pour the hydrochloric acid into a conical flask, ensuring precision by reading at eye level and using a pipette for the final drops. The first method shown involves inverting a measuring cylinder filled with water to capture the gas produced by the reaction, with careful attention to avoiding air bubbles and ensuring the cylinder is clamped securely. The gas production is measured every 10 seconds, and the process is repeated with the lower concentration of hydrochloric acid to observe differences in reaction rates. An alternative method using a gas syringe is also introduced, emphasizing the need to keep the syringe dry to prevent errors. The video concludes with a discussion on how to graph the results, comparing the rates of reaction based on the steepness of the curves on the graph, and highlights potential sources of error in the experiment, such as the imprecision of the measuring cylinder and the difficulty in coordinating the start of the reaction.
Mindmap
Keywords
💡Chemical Reaction
💡Rate of Reaction
💡Measuring Cylinder
💡Gas Syringe
💡Hydrochloric Acid
💡Magnesium
💡Concentration
💡Volume of Gas
💡Reaction Rate Graph
💡Limiting Reactant
💡Sources of Error
Highlights
Introduction to measuring the rate of a chemical reaction using two methods: a measuring cylinder and a gas syringe.
Demonstration of using magnesium and hydrochloric acid for the reaction.
Comparison between two different concentrations of hydrochloric acid: 2 moles per decimeter cubed and 1 mole per decimeter cubed.
Procedure for measuring 50 centimeters cubed of 2 molar hydrochloric acid using a measuring cylinder.
Technique for eliminating air bubbles in the measuring cylinder by inverting it under water.
Instructions on clamping the measuring cylinder and recording gas production every 10 seconds.
Use of a delivery tube to direct the gas into the measuring cylinder.
Observation that the 2 molar hydrochloric acid produces gas faster than the 1 molar.
Alternative method using a gas syringe to measure gas production.
Importance of keeping the gas syringe dry to avoid errors.
Methodology for collecting data on gas production every 10 seconds.
Graphing results with time on the x-axis and volume of gas on the y-axis.
Explanation of how the reaction rate is indicated by the steepness of the curve on the graph.
Understanding that the reaction stops when the limiting reactant, magnesium, is fully reacted.
Identification of potential sources of error, such as timing inaccuracies and hydrogen loss at the start of the reaction.
Discussion on the imprecision of the measuring cylinder and the benefits of using an inverted burette for greater precision.
Transcripts
hi there it's mr. Mitchell here from
Mars for science and today we'll be
looking at the second of two videos
measuring a rate of a chemical reaction
I'm going to show you two methods to
measure the rate of a chemical reaction
today firstly using a measuring cylinder
and secondly a gas syringe for action
today I'm going to using magnesium and
hydrochloric acid I'm going to be
comparing two different concentrations
of hydrochloric acids I'm going to be
looking at two moles per decimeter cubed
against one mol per decimeter cubes 2
mol per decimeter cubed means for every
decimates acute of water I have every
litre of water
I am dissolving two models of
hydrochloric acid in the solution I'm
going to start by measuring 50
centimeters cubed of 2 mol per decimeter
cubed hydrochloric acid in a measuring
cylinder I'm going to pour the first 45
making sure I read at eye level to see
the bottom of the meniscus as I get
close I'm going to use a pipette to add
the final few drops I'm going to pour
the hydrochloric acid into a conical
flask with a bung and delivery tube the
first method I'm going to show you is a
measuring cylinder filled with water and
inverted that the gas will displace as
it's produced push the measuring
cylinder into the trough and then slowly
lower the top of the measuring cylinder
down to fill it with water this will
eliminate the risk of getting any air
bubbles in the measuring cylinder you
then need to clamp the measuring
cylinder in place about one centimeter
off the bottom of the trough make sure
that you can see the scale on the
measuring cylinder because you're going
to need to record the gas being produced
every 10 seconds put the delivery tube
into the bottom of the measuring
cylinder like so
you're going to add the magnesium to the
conical flask and as you do this your
part is going to start the stop clock at
the same time you're going to have to
put the bunk immediately onto the top of
the conical flask making sure there's no
room for the gas to escape as the gas is
produced water is forced out to the
measuring cylinder you need to count how
much gas has been produced every 10
seconds and record it in your results
table this time I'm using the 1 molar
hydrochloric acid to see if the
reactions are little bit slower I'm
going to once again pour the
hydrochloric acid into the conical flask
and as you add the magnesium into the
burners start the timer at the same time
once again we're measuring the gas
produced every 10 seconds
an alternative method is to use a gas
syringe we're still using a conical
flask bung and delivery tube with the
hydrochloric acid in magnesium however
you're measuring how much gas fills up
the gas syringe
once again measuring the amount of gas
produced every 10 seconds
the gas syringe needs to be kept dry at
all times otherwise there's a risk of
the plunge getting stuck and you won't
be able to get any results
now you've collected results of
different concentrations you're going to
draw a graph of your results on your
graph you'll have time along the x-axis
in seconds and volume of gas collected
every 10 seconds in centimeters cubed
on the y-axis as you can see the two
molar hydrochloric acid has a much
steeper curve than the 1 molar
hydrochloric acid therefore has a faster
rate of reaction the results reach the
same point that's because we use an
excess of hydrochloric acid for this
reaction that means that the magnesium
is the limiting reactant the reaction
will stop when all of the magnesium has
reacted and so that means there's only a
certain volume of gas that can be
produced there are some sources of error
to be aware of in this reaction firstly
the fact that we are starting the timer
putting the bung in the conical flask
and adding the magnesium all at the same
time is impossible this means it's going
to have you and a partner doing this
reaction as it be very difficult on your
own also some hydrogen may be lost at
the start of the reaction and that the
source of error is that the measuring
cylinder is quite imprecise because we
can only read every one centimeter cubed
of gas that's collected if we were to
use an inverted burette this would be
much more precise as we can see every
naught point 1 centimeter cubed of gas
collected and therefore have a greater
degree of precision in our result
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