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CHEMISTRY, M5 2023 HSC 4 MC

Sodium chloride dissolves in water according to the following equation.

A saturated solution of in water contains sodium and chloride ions at the following concentrations.
 

  
  
What is the of sodium chloride?
 
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CHEMISTRY, M5 EQ-Bank 29

The information in the table shows how the solubility of lead chloride is affected by temperature.  
 

Using a graph, calculate the solubility product of the dissolution of lead chloride at 50°C. Include a fully labelled graph and a relevant chemical equation in your answer   (6 marks)
 

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CHEMISTRY, M5 EQ-Bank 28

A 100 mL saturated solution of calcium hydroxide at 25°C contains 0.173 g of calcium hydroxide.

  1. Calculate the solubility product of this salt at 25°C.  (3 marks)

  2. Explain why the undissolved solid is not included in the expression for the solubility product constant.  (1 marks)

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a.    

b.    → is constant throughout the reaction.

→ Since it does not change, it is not included in the equilibrium expression.

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a.   


 

 


 

 

b.    → is constant throughout the reaction.

→ Since it does not change, it is not included in the equilibrium expression.

CHEMISTRY, M5 2022 HSC 35

A precipitate of strontium hydroxide , ( = 121.63 g mol ¯1) was produced when 80.0 mL of 1.50 mol L ¯1 strontium nitrate solution was mixed with 80.0 mL of 0.855 mol L ¯1 sodium hydroxide solution. The mass of the dried precipitate was 3.93 g.

What is the of strontium hydroxide?   (5 marks)

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♦ Mean mark 43%

CHEMISTRY, M5 2021 HSC 27

An experiment is carried out to determine the value for lithium phosphate .

Five samples of ion solution were prepared, and a different solution of was added to each of them. Columns 2 and 3 of the table show the values before any reaction occurs.
 

  1. Calculate the range within which the value of lithium phosphate lies.   (4 marks)

  2. Justify ONE way in which the procedure of this investigation could be improved to increase the accuracy of the calculated result.  (2 marks)

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a.  is between the range of    and  .
 

b.   Answers could include one of the following.

→ Add more solutions of    ions between the concentrations of 0.010 mol L¯1 and 0.10 mol L¯1, thus increasing the accuracy of the estimated SI value.

→ Form a precipitate titration by titrating the ions against a ion solution until a precipitate is formed. This would allow the experimental value to be closer to the correct SI value for lithium phosphate, and in turn increase the accuracy of the calculated results.

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a.   

 

To calculate the range, we compare the point just before no precipitation occurs to the point when the precipitation first occurs.

Sample 3:

 

Sample 4:

 

Therefore the is between the range of    and 


♦ Mean mark (a) 50%.

b.   Answers could include one of the following.

→ Add more solutions of    ions between the concentrations of 0.010 mol L¯1 and 0.10 mol L¯1, thus increasing the accuracy of the estimated SI value.

→ Form a precipitate titration by titrating the ions against a ion solution until a precipitate is formed. This would allow the experimental value to be closer to the correct SI value for lithium phosphate, and in turn increase the accuracy of the calculated results.


Mean mark (b) 52%.