Lithium, sodium and potassium are reactive metals in group 1 of the periodic table - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2018 - Paper 1
Question 6
Lithium, sodium and potassium are reactive metals in group 1 of the periodic table.
(a) Sodium metal tarnishes in air to form a layer of sodium oxide on its surface... show full transcript
Worked Solution & Example Answer:Lithium, sodium and potassium are reactive metals in group 1 of the periodic table - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2018 - Paper 1
Step 1
Calculate the moles of sodium and oxygen
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Answer
To find the moles of sodium, use the formula:
ext{Moles} = rac{ ext{Mass}}{ ext{Molar mass}}
For sodium:
ext{Moles of Na} = rac{0.92}{23} = 0.04 ext{ moles}
For oxygen:
ext{Moles of O} = rac{0.32}{16} = 0.02 ext{ moles}
Step 2
Determine the simplest mole ratio
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Next, divide both quantities by the smallest number of moles:
ext{Ratio of Na} = rac{0.04}{0.02} = 2\ ext{Ratio of O} = rac{0.02}{0.02} = 1
Thus, the simplest ratio of sodium to oxygen is 2:1.
Step 3
Write the empirical formula
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From the ratio, the empirical formula of sodium oxide can be written as:
extNa2extO
Step 4
Complete the balanced equation
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The balanced equation for the reaction of sodium with water is:
