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CHEMISTRY, M2 EQ-Bank 6

During a laboratory experiment, 32.0 grams of oxygen gas is required. Calculate the number of molecules of oxygen gas needed.   (2 marks)

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molecules.

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Calculate the number of moles of oxygen gas ():

 
 

Use Avogadro’s number to find the number of molecules:

 

→ Oxygen gas required = molecules.

CHEMISTRY, M2 EQ-Bank 4

A propane tank contains 10.0 kg of propane . How many moles of propane are in the tank?   (2 marks)

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Calculate the number of moles of propane ():

 

→ The number of moles of propane in the tank is 226.8 mol.

CHEMISTRY, M2 2012 VCE 18 MC

2.1 g of an alkene that contains only one double bond per molecule reacted completely with 8.0 g of bromine, . The molar mass of bromine, , is 160 g mol.

Which one of the following is the molecular formula of the alkene?

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→ Since each molecule only contains a single bond:

CHEMISTRY, M2 2012 VCE 15*

A sample of the anticancer drug Taxol, , contains 0.157 g of carbon.

Calculate the mass, in grams, of oxygen in the sample. Give your answer correct to three decimal places.   (2 marks)

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CHEMISTRY, M2 2006 HSC 18

A student studying the mass change that occurs during fermentation added glucose, water and yeast to a flask and stoppered the flask with some cotton wool.

The student measured the mass of the flask daily for seven days. The table shows the data collected.

  1. Calculate the moles of released between days 1 and 7.  (1 mark)

  2. Calculate the mass of glucose that underwent fermentation between days 1 and 7. Include a balanced chemical equation in your answer.  (3 marks)

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a.    59.37 moles

b.    5395.92 g

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a.   

 

b. 

→ The moles of released and the reaction’s molar ratio can be used to calculate the mass of glucose that underwent fermentation.

→ Molar ratio between glucose and carbon dioxide =

CHEMISTRY, M2 2009 HSC 22

The nitrogen content of bread was determined using the following procedure:

    • A sample of bread weighing 2.80 g was analysed.
    • The nitrogen in the sample was converted into ammonia.
    • The ammonia was collected in 50.0 mL of 0.125 mol L hydrochloric acid. All of the ammonia was neutralised, leaving an excess of hydrochloric acid.
    • The excess hydrochloric acid was titrated with 23.30 mL of 0.116 mol L sodium hydroxide solution.
  1. Write balanced equations for the TWO reactions involving hydrochloric acid.  (2 marks)

  2. Calculate the moles of excess hydrochloric acid.  (1 mark)

  3. Calculate the moles of ammonia.   (2 marks)

  4. Calculate the percentage by mass of nitrogen in the bread.  (2 marks)

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a.   

b.   

c.   

d.   

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a.   


 

b.   
 

c.   


 

d.