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The diagram shows a model of a water molecule - Edexcel - GCSE Chemistry - Question 4 - 2012 - Paper 1
Question 4
The diagram shows a model of a water molecule. hydrogen atom. oxygen atom covalent bond a) Explain, in terms of electrons, how a covalent bond is formed between ... show full transcript
Worked Solution & Example Answer:The diagram shows a model of a water molecule - Edexcel - GCSE Chemistry - Question 4 - 2012 - Paper 1
Step 1
Explain, in terms of electrons, how a covalent bond is formed between an oxygen atom and a hydrogen atom.
Answer
A covalent bond is formed when an oxygen atom shares its outer electrons with hydrogen atoms. Oxygen has six electrons in its outer shell and needs two more to fill it. Each hydrogen atom has one electron and can share it with oxygen. Thus, one oxygen atom forms two covalent bonds with two hydrogen atoms, leading to the formation of a water molecule (H₂O).
Step 2
Calculate the relative formula mass of water, H2O.
Answer
To calculate the relative formula mass of water (H₂O):
- Hydrogen (H) has a relative atomic mass of 1.0, and there are 2 hydrogen atoms. Thus, the mass contribution from hydrogen is: [ 2 \times 1.0 = 2.0 ]
- Oxygen (O) has a relative atomic mass of 16.0. Thus, the mass contribution from oxygen is: [ 1 \times 16.0 = 16.0 ]
- Adding these contributions gives: [ 2.0 + 16.0 = 18.0 ] Therefore, the relative formula mass of water is 18.0.
Step 3
Step 4
Calculate the percentage yield.
Answer
The percentage yield can be calculated using the formula:
[ \text{Percentage Yield} = \left( \frac{\text{actual yield}}{\text{theoretical yield}} \right) \times 100 ] In this case, the actual yield is 2.0 g and the theoretical yield is 4.0 g:
[ \text{Percentage Yield} = \left( \frac{2.0}{4.0} \right) \times 100 = 50% ]
Step 5