Spreadsheet

UNIVERSITI PENDIDIKAN SULTAN IDRIS (UPSI)

NAMA KURSUS TEKNOLOGI KOMUNIKASI DAN MAKLUMAT DALAM KIMIA KOD KURSUS TKU 3023

TAJUK SPREADSHEETS : EFFECT OF CATALYST ON THE RATE OF REACTION

NAMA PENSYARAH PN ASMAYATI YAHYA

NAMA

NO MATRIK

WAN NUR AIN BINTI WAN MOHAMED KASBI

D20081032255

NOR HIDAYAH BT ABDUL LATIFF

D20081032346

EFFECT OF CATALYST ON THE RATE OF REACTION Teacher’s Guide / Chemistry Form 5 / Spreadsheet

SCIENTIFIC CONCEPT A catalyst is a substance which speeds up a reaction by provides an alternative route for the reaction with a lower activation energy, but it is chemically unchanged at the end of the reaction. When the reaction has finished and completed, the mass of catalyst is exactly same as had in the beginning of reaction. To increase the rate of reaction, the frequency of an effective collisions must be increase. Adding a catalyst has exactly effect on activation energy. A catalyst provide an alternative route for the reaction. That alternative route has a lower activation energy that showing in this energy profile:

What happens if we add a catalyst to a chemical system that is in equilibrium? A catalyst lowers the activation barrier between the reactants and products. The activation energy of the forward reaction is lowered to the same extent as that for the reverse reaction. The catalyst thereby increases the rates of both the forward and reverse reactions. As a result, a catalyst increases the rate at which equilibrium is achieved, but it does not change the composition of the equilibrium mixture. The value of the equilibrium constant for a reaction is not affected by the presence of a catalyst.

UNIQUE FEATURE OF ACTIVITY This activity requires the student to understand the effect of using a catalyst on the rate of reaction. In this activity, the mass of catalyst are change in order to observe how the mass of catalyst can affect the rate of reaction. Students will observe that the addition of a catalyst increase the rate of production of oxygen from hydrogen peroxide. From the experiment that had done, students are required to calculate the rate of reaction by using certain formula. The unique of using spreadsheets are: •

The ability to tabulate data and help students to calculate the answer. This allows the removal of tedious and drudgery calculation. The spreadsheet must be set up first. When students have set up the spreadsheet, they can just enter the data in the table and the value of the rate of reaction for the different quantity of catalyst will appear on the column of the formula. The formula of the rate of reaction is:

Rate of reaction = Change in volume of oxygen gas produced ( cm3) Time taken ( s ) = ......................cm3s-1

•

Spreadsheets are very practical and suitable for repetitive calculation. For example, if the students change the value of quantity of catalyst, the volume of oxygen gas produced and the rate of reaction will also change. The points on the graph will also automatically change according to the data entered. This allows the students to do more important things in science and no recalculations or re- graphing needed.

ENGAGE

USING A CATALYST There are two ways to go to the particular place. Which one of the ways can save our energy and time taken to go to that place?

Effect of using catalyst is like we take an alternative ways that can save time and energy.

EMPOWER 1. Students plan an experiment to investigate the effect of using different quantity of catalyst on the rate of reaction.

2. Students are given the following apparatus: a) A 50 cm3 measuring cylinder

b) Erlenmeyer flask c) Burette d) Retort stand and clamp e) Stop watch f) Basin g) Glass tubing 3. The reagents that used in this experiment are: a) 20 cm3 of hydrogen peroxide solution

b) Mangan ( IV ) oxide powder

c) Distilled water 4. Students are required to plan an experiment to show that a quantity of catalyst influence the number of oxygen gas produce and the rate of reaction. 5. Students have construct a hypothesis before doing the experiment. Hypothesis is a general statement about the relationship between a manipulated variable and a responding variable in order to explain an observation. It is tested to determine its validity. 6. The procedure of conducting the experiment is discussed. 7. By using the formula of: Rate of reaction = Change in volume of oxygen gas produced ( cm3) Time taken ( s ) Students are find the value of rate of reaction for both the quantity of catalyst using the spreadsheet program. 8. An experiment involves the following steps: a) Identifying a problem b) Making a hypothesis c) Planning the experiment d) Conducting the experiment e) Collecting data f) Analysing data g) Interpreting data h) Making conclusions i) Writing a report

Result :

QUESTIONS: 1. How do catalyst affect the rate of reaction? 2. Plot a graph of total volume of oxygen gas released against time for experiment I and experiment II on the same axis. 3. How did the rates of experiment I and experiment II differ? 4. Which experiment shows the higher rate of decomposition of hydrogen peroxide? 5. If the experiments are allowed to proceed until completion, is the total volume of gas collected in both experiments are same? Explain your answer.

ANSWER : 1. Catalyst speed up chemical reactions. Only very minute quantities of the catalyst are required to produce a dramatic change in the rate of reaction. This is because the reaction proceeds by a different pathway when catalyst is present. Adding extra catalyst will make absolutely no difference. 2.

Total volume of oxygen ( cm3 )

Time ( s ) 3. The rates of experiment I and experiment II are differ because the quantity of catalyst present are variable. When the quantity of catalyst present are increase, the rate of reaction also increase. 4. Experiment II show the higher rate of decomposition of hydrogen peroxide. 5. Yes, the total volume of gas collected in both experiment are same. It is because catalyst just speed up a reaction by proceed a different pathway. Adding extra catalyst will make absolutely no difference.

ENHANCE A word of caution! "A catalyst provides an alternative route for the reaction with a lower activation energy." It does not "lower the activation energy of the reaction". There is a subtle difference between the two statements that is easily illustrated with a simple analogy. Suppose you have a river between two jungle so that the only way for people to get from one jungle to the another jungle is over the river. Only the most active people will manage to get from one jungle to the other. Now suppose a bridge is ties between the two jungle. Many more people will now manage to get from one jungle to the other by this easier route. You could say that the bridge route has a lower activation energy than swim in the river. But we haven't narrow the river! The bridge has provided an alternative route but hasn't narrow the original one. The original river is still there, and some people will still choose to swim in it. In the chemistry case, if particles collide with enough energy they can still react in exactly the same way as if the catalyst wasn't there. It is simply that the majority of particles will react via the easier catalysed route.