A student is asked to investigate the initial rate of reaction for the chemical reaction between magnesium and nitric acid
Mg (s) + 2HNO3 (aq) → Mg(NO3)2 (aq) + H2 (g)
Alongside a timer, which piece of equipment would be the most appropriate to determine the initial rate of reaction?
Colorimeter
Gas syringe
Balance
Burette
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The pH curve for the reaction of a weak acid with a strong base is shown.
Which row shows the correct location of the chemicals used for this reaction?
|
|
Burette |
Conical flask |
|
A |
Ammonia |
Ethanoic acid |
|
B |
Hydrochloric acid |
Sodium hydroxide |
|
C |
Sodium hydroxide |
Ethanoic acid |
|
D |
Ethanoic acid |
Sodium hydroxide |
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There are several different methods for measuring reaction rates.
Which of the following reactions cannot have their reaction rate measured using the method suggested?
| Reaction | Method used | |
| A |
H2O2 (aq) + 2I– (aq) + 2H+ (aq) → 2H2O (l) + I2 (aq) |
Colorimetry |
| B | Mg (s) + 2HNO3 (aq) → Mg(NO3)2 (aq) + H2 (g) | Measurement of the change of mass |
| C |
HCOOH (aq) + Br2 (aq) → 2H+ (aq) + 2Br– (aq) + CO2 (g) |
Measurement of the change in volume of a gas |
| D | HCOOCH3 (aq) + NaOH (aq) → HCOONa (aq) + CH3OH (aq) | Titrating samples of the reaction mixture with acid |
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The following chemical tests were performed on ethanoic acid, hydrochloric acid and sulfuric acid.
| Chemical test | Result |
| Universal indicator solution | Turns red |
| pH probe | Records value between 1.0 and 2.0 |
| Phenolphthalein | Remains colourless |
Which of the chemicals could produce the results shown?
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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What is the pH of a buffer solution containing 0.80 mol dm-3 solution of ethanoic acid, CH3COOH, and 0.80 mol dm-3 sodium ethanoate, CH3COONa at 25 ℃?
(Ka of ethanoic acid at 25 ℃ = 1.78 x 10-5 mol dm-3)
0.10
5.75
3.75
4.75
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In a rate experiment 1.5 mol dm-3 hydrochloric acid was reacted with 0.25 g of magnesium. The volume of gas produced was collected in a 100 cm3 gas syringe.
A graph was produced and a tangent was drawn at (0,0). The following points (9,38), (14,59) and (18,76) lie on this tangent.
Calculate the initial rate.
0.24 cm3 s-1
0.24 mol dm-3 s-1
4.22 cm3 s-1
4.22 mol dm-3 s-1
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Which of the following statements about the iodine clock reaction is/are correct?
|
Concentration of potassium iodide (mol dm-3) |
Time for blue colour to appear (s) |
|
0.840 |
2.50 |
|
1.680 |
1.20 |
|
3.360 |
0.63 |
|
6.720 |
0.32 |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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A series of reactions of ethanedioic acid and potassium manganate(VII) was carried out at different temperatures. The gas constant is 8.31 J K-1 mol-1.
2MnO4– (aq) + 5H2C2O4 (aq) + 6H+ (aq) → 2Mn2+ (aq) + 8H2O (l) + 10CO2 (g)
The following data was collected.
|
Temperature, K |
Rate (1/t), s-1 |
|
295 |
0.016 |
|
309 |
0.031 |
|
317 |
0.043 |
|
322 |
0.053 |
|
336 |
0.067 |
What is the activation energy (Ea) for this reaction?
29200 kJ mol-1
29.2 kJ mol-1
10.3 kJ mol-1
10300 kJ mol-1
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A student wants to make 100 cm3 of a buffer solution between ethanoic acid and sodium ethanoate with a pH of 5.50. They start with 10 cm3 of 0.40 mol dm-3 ethanoic acid.
pKa of ethanoic acid is 4.76.
What is the mass of sodium ethanoate needed for this buffer solution?
0.018 g
0.180 g
1.800 g
1.318 g
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Which statement about rate of reaction practicals is/are correct?
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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The initial rate of reaction between marble chips and dilute acid can be determined by measuring the volume of gas given off per unit time and plotting a graph of the results.
What is the reason for plotting a graph of the results?
The rate of reaction is a more accurate value
Outliers in the results can be spotted and discarded
An average rate can be determined from the graph
The rate of reaction can be found more precisely
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The following partially drawn pH curve was obtained in an experiment:
Which of the following could be true?
| Label for x-axis |
Solution in burette |
Solution in conical flask |
|
| A | Volume of acid | HCl | NH3 |
| B | Volume of base | NaOH | CH3COOH |
| C | Volume of acid | CH3COOH | NaOH |
| D | Volume of base | NaOH | HCl |
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Which of the following combinations could be used to make a buffer solution?
40 cm3 of 0.1 mol dm-3 CH3COOH + 40 cm3 of 0.05 mol dm-3 NaOH
40 cm3 of 0.1 mol dm-3 CH3COOH + 40 cm3 of 0.1 mol dm-3 NaOH
20 cm3 of 0.1 mol dm-3 CH3COOH + 20 cm3 of 0.2 mol dm-3 NaOH
40 cm3 of 0.1 mol dm-3 CH3COOH + 20 cm3 of 0.2 mol dm-3 NaOH
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This question is about drawing curves and obtaining gradients in chemistry investigations.
Which of the following is not true?
There are an equal number of points on either side of the line of best fit
The hypotenuse of the gradient triangle includes at least half of the line
The gradient triangle starts and ends on points where the line of best fit crosses grid lines
The gradient in this graph is 
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The reaction of hydrogen peroxide with iodide ions in acid solution can be set up as a clock reaction:
H2O2 (aq) + 2H+ (aq) + 2I- (aq) → I2 (aq) + 2H2O (l)
The reaction is first order with respect to iodide ions. A student performed an experiment to determine the order of this reaction they calculated a value of 0.963.
What is the percentage error in this result?
0.97%
0.04%
3.7%
1.03%
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