Year 11 Chemistry Practical Exam #2

Question 1.

1. A 1000 g rock contains 15% CaCO₃, how many Ca atoms are there? [4 marks]
2. How many oxygen atoms are there in the CaCO₃ component of the rock? [1 mark]

Question 2.

1. A sample of NaCl powder is dissolved in water 600 g of water – if the mass after it is dissolved is 610 g, what is the concentration of NaCl in the solution? [4 marks]
2. A sample of NaF powder is dissolved in water 100g of water – if the mass after it is dissolved is 105 g, what is the concentration of NaF in the solution? [4 marks]

Question 3.

If a student evaporated all of the water from CuSO₄, which, when it was originally measured out and before dissolved in water it had a molar ratio of 1:6 of CuSO₄ to H₂O. If The final mass of CuSO₄ was 50 g after evaporating, how many grams were added initially? [5 marks]

Question 4.

1. Draw the following as a scientific diagram 

2. Explain a potential source of error in the above diagram, and how you could avoid this
3. Why is a blue flame used above instead of a safety flame?

Question 5.

When Calcium carbonate is reacted with hydrochloric acid, two of the three by-products formed are carbon dioxide and water. Write out the net ionic equation for this reaction [2 marks]

Answer.

1a) 4.5 *10^23 Ca atoms

b) 1.36 *10^23 O atoms

2a) 0.285 M

b) 1.193 M

4) 536 g