Calcium Hydroxide

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1aThe diagram shows the parts of a hydrogen atom.

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Use words from the list to label the diagram.
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bHydrogen can be used as a clean fuel for cars.
iWhen hydrogen burns in air, it reacts with another element.
Complete the word equation for this reaction.
hydrogen + ................... → water(1)
iiSuggest one reason why hydrogen is called a clean fuel.

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AQA, 2008

2Use a periodic table to help you to answer this question.
Oxygen is in Group 6 of the periodic table.
aiHow many protons are in an atom of oxygen?

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iiHow many electrons are in an atom of oxygen?

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bChlorine is in Group 7 of the periodic table.
Complete the electronic structure of chlorine: 2, ...........(1)
cFluorine is also in Group 7.
Explain why in terms of electronic structure.

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dNeon and argon are in Group 0 of the periodic table. They are very unreactive elements. What does this tell you about their electronic structures?

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3When calcium carbonate is heated it decomposes. The equation for this reaction is:
CaCO3 → CaO + CO2
aUse numbers from the list to complete the sentences.
23456
iThe number of products in the equation is ....... (1)
iiThe formula CaCO3 shows that calcium carbonate was made from ....... different elements.
iiiThe equation is balanced because there are ....... atoms on both sides.(1)(3)
bOther metal carbonates decompose in a similar way.
iName the solid produced when zinc carbonate decomposes.

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iiName the gas produced when copper carbonate decomposes.

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4Farmers can use calcium hydroxide to neutralise soils that are too acidic. Limestone is mainly calcium carbonate, CaCO3.
Limestone is used to make calcium hydroxide, Ca(OH)2.
aWhat are the two reactions used to make calcium hydroxide from limestone?

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bExplain why calcium hydroxide neutralises soils that are too acidic.

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cFarmers can also use powdered limestone to neutralise soils that are too acidic. Explain why.

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dSuggest one reason why it may be safer for farmers to use powdered limestone instead of calcium hydroxide.

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eSuggest one reason why powdered limestone costs less than calcium hydroxide.

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fWrite balanced equations for the reactions in 4(a)

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gThe formula of calcium chloride is CaCl2. Write a balanced equation for the reaction of calcium hydroxide with hydrochloric acid, HCl.

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hWrite a balanced equation for the reaction of calcium carbonate with hydrochloric acid.

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5Titanium is as strong as steel but is much more expensive. It is used to make jet engines for aircraft and to make replacement hip joints for people.
aGive two properties that make titanium better than steel for making jet engines and replacement hip joints.

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bIn this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Titanium is made in batches of about 10 tonnes that takes up to 15 days. The main steps to make titanium are: Titanium oxide is reacted with chlorine to produce titanium chloride. Titanium chloride is reacted with magnesium at 900°C in a sealed reactor for three days to give a mixture of titanium and magnesium chloride. The reactor is cooled for 7 days, and then the mixture is removed. The magnesium chloride is removed from the mixture by distillation at very low pressure. The titanium is melted in an electric furnace and poured into moulds.

Steel is produced at about 8000 tonnes per day. The main steps to make steel are: Iron oxide is reacted with carbon...
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