Bloggeroid for Blogger (BFB)

BFB a brand new apps that I just installed from the playstore. well, at least its new for me. hopefully this apps works better than the previous apps that id installed. "the officially blogger" haha what a full of shame apps I guess. I hope this works well too.

*on my way to press the 'publish' botton on the right hand side of my phone.*

PEKA Chemistry form 5 chapter 1 (To study the effect of a catalyst on the rate of reaction.)

Aim                             : To study the effect of a catalyst on the rate of reaction.

Problem statement      : How does a catalyst affect the rate of reaction?

Hypothesis                  : The presence of a catalyst increases the rate of reaction.

Variables                     :-

Manipulated variable  : Presence or absence of a catalyst.

                                    Responding variable   : Rate of reaction.

Controlled variables   : Volume and concentration of hydrochloric acid, HCl, mass of zinc powder

Operational definition : The changes of gas volume are measured in intervals of 30 seconds when a catalyst is presence or absence when zinc power, Zn, is added to hydrochloric acid, HCl.

Apparatus                    : 50cm3 measuring cylinder, 100cm3 conical flask, rubber stopper with delivery tube, burette, retort stand with clamp, stopwatch, basin, electronic balance

Materials                     : 0.1 mol dm-3 hydrochloric acid, HCl, zinc power, 0.5mol dm-3 copper sulphate, CuSO4, solution, water

Procedure                    :-

                                    !@#$%^&*()_+?><}|{:”

1.      50cm3 of 0.1 mol dm-3 hydrochloric acid, HCl, is measured with a measuring cylinder and the poured into the conical flask.

2.      5g of zinc power, Zn (Set I) is weighed with an electronic balance.

3.      The basin and the burette are filled with water. The burette is inverted in the basin and clamped vertically with a retort stand.

4.      The water level in the burette is adjusted so that the reading of the water level is almost at 50cm3.

5.      Pour the zinc powder, Zn, that have been weighed into the conical flask which filled with hydrochloric acid, HCl.

6.      The conical flask is immediately covered with a rubber stopper which is joined to the delivery tube. The gas released been channeled into the burette and the stopwatch is started at the same time.

7.      The conical flask is shaken slowly throughout the experiment.

8.      The burette readings are recorded at intervals of 30 seconds for 5 minutes.

9.      Steps 1 to 8 are repeated by adding 5cm3 of 0.5mol dm-3 copper sulphate, CuSO4, solution (Set II) into the conical flask. The other conditions remain unchanged.

10.  The results are recorded in a table.

11.  The volume of hydrogen, H, gas collected are measured.

Data and observations            :-

Interpreting data         :-

1.      Based on the results, a graph of the total volume of hydrogen gas, H2, collected against time for sets I and II is drawn on the same axis.

2.      Based on the graph plotted, determine 

(a)    The overall average rates of reaction for

(i)                 Set I

-           

(ii)               Set II

-

(b)   The rates of reaction at 90^th seconds

(i)                 Set I

-

(ii)               Set II

-

3.      Compare the rates of reaction for both sets of experiments.

Discussion                   :-

           

1.      Write down the chemical equation for the reaction between hydrochloric acid, HCl, and zinc powder.

-          2HCl + Zn à ZnCl2 + H2

2.      What the effect of copper sulphate, CuSO4, solution on the rate of reaction.

3.      A student found that the volume of hydrogen, H2, gas collected for both sets of experiments was the same. What can you conclude about the presence of copper sulphate, CuSO4, solution and the total volume of gas collected?

Conclusion                  : Hypothesis is accepted. The presence of a catalyst increases the rate of reaction.

PEKA Chemistry form 5 chapter 1 (To study the effect of temperature on the rate of reaction.)

Aim                             : To study the effect of temperature on the rate of reaction.

Problem statement      : How does the temperature of sodium thiosulphate, Na2S2O3, solution affect the rate of reaction?

Hypothesis                  : The rate of reaction will increase if the temperature of sodium thiosulphate, Na2S2O3, solution increases.

Variables                     :-

Manipulated variable  : Temperature of sodium thiosulphate, Na2S2O3, solution. (reaction)

                                    Responding variable   : Rate of reaction.

Controlled variables   : Volume and concentration of sulphuric acid, H2SO4, volume and concentration of sodium thiosulphate, Na2S2O3, solution.

Operational definition : The time taken for the mark “X” to disappear from sight in different temperature when the sodium thiosulphate, Na2S2O3, solution react with sulphuric acid, H2SO4

The rate of reaction is measured by how fast the 'X' is hidden by the yellow precipitate.

Apparatus                    : 50cm3 measuring cylinder, 100cm3 conical flask, 10cm3 measuring cylinder, stopwatch, thermometer, Bunsen burner, wire gauze, tripod stand

Materials                     : 0.2 mol dm-3 sodium thiosulphate, Na2S2O3, solution, 0.1mol dm-3 sulphuric acid, H2SO4, white paper marked “X” at the centre

Procedure                    :-

                                    !@#$%^&*()_+?><}|{:”

1.      An “X” is marked using a pencil on the centre of a piece of white paper.

2.      50cm3 of 0.2 mol dm-3 sodium thiosulphate, Na2S2O3, solution is measured with a 50cm3 measuring cylinder and is poured into a conical flask.

.

3.      Using a 10cm3 measuring cylinder, 5cm3 of 0.1mol dm-3 sulphuric acid, H2SO4 is measured.

4.      The sodium thiosulphate, Na2S2O3, solution is heated with a Bunsen burner and quickly placed on the “X” mark on the piece of white paper when it reaches 30c.

5.      Sulphuric acid, H2SO4 is immediately and carefully poured into the conical flask containing 50cm3 of 30c of sodium thiosulphate, Na2S2O3, solution. At the same time, the stopwatch is started.

6.      The conical flask is shaken slowly throughout the experiment on the white paper.

7.      The mark “X” is observed vertically from the top part of the conical flask through the solution.

8.      The stopwatch is stopped quickly as the mark “X” on the white paper is no longer visible.

9.      The time taken, for the mark “X” to disappear from sight is recorded.

10.  Steps 1 to 9 are repeated four more times using different temperature of 0.2 mol dm-3 sodium thiosulphate, Na2S2O3, solution at 35c, 40c, 45c and 50c. Whereas the other conditions remain unchanged.

11.  The results are recorded in a table.

Data and observations            :-

Temperature of sodium thiosulphate, Na2S2O3, solution/ c	30	35	40	45	50
Time/ s	9.8	8.7	8	6	5.2
1/time/ s-1

Interpreting data         :-

1.      Based on the results, two graphs are plotted.

(a)    The graph of the temperature of sodium thiosulphate, Na2S2O3, solution against the time taken for the mark “X” to disappear from sight.

(b)   The graph of the temperature of sodium thiosulphate, Na2S2O3, solution against 1/time.

2.      Based on the graph plotted, determine the relationships between the temperature of sodium thiosulphate, Na2S2O3, solution with  

(a)    The time taken

-          As the temperature of sodium thiosulphate, Na2S203, solution decreases, a longer time is needed for mark ‘X’ to disappear from sight.  Therefore, as the temperature becomes lower, the rate of reaction also decreases.

(b)   1/time

-          The temperature rises, the value of 1/time or rate of reaction also increases.

3.      Deduce the effect of the temperature a reactant on the rate of reaction.

-          The relationship between the rate of reaction and the temperature of sodium thiosulphate, Na2S2O3, solution is, when the temperature of a reactant increases, the rate of reaction increases.

Discussion                   :-

           

1.      Write down the chemical equation for the reaction between sodium thiosulphate, Na2S2O3, solution and dilute sulphuric acid, H2SO4.

-          S₂O_3(aq)   +   2H_(aq)   →   S_(s)   +   SO_2(g)   +   H₂O_(l)

2.      Name the yellow precipitate which is formed throughout the experiment?

-          The yellow precipitate formed is sulphur.

3.      Why are the volume and concentration of both the sodium thiosulphate, Na2S2O3, solution and sulphuric acid, H2SO4 used remain constant for each set of the experiment?

-           

Conclusion                  : Hypothesis is accepted. The rate of reaction will increase if the temperature of sodium thiosulphate, Na2S2O3, solution increases.