If liquid water is cooled below 0°C it turns into the solid, ice - Edexcel - GCSE Chemistry - Question 2 - 2021 - Paper 1
Question 2
If liquid water is cooled below 0°C it turns into the solid, ice.
(a) (i) Give the name for the change of state from liquid to solid.
(ii) Here are five statements... show full transcript
Worked Solution & Example Answer:If liquid water is cooled below 0°C it turns into the solid, ice - Edexcel - GCSE Chemistry - Question 2 - 2021 - Paper 1
Step 1
Give the name for the change of state from liquid to solid.
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Answer
The change of state from liquid to solid is called freezing or solidification.
Step 2
Place ticks in boxes by the two statements that are correct.
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Answer
The two correct statements are:
the molecules are more randomly arranged in ice than in water
the molecules are arranged regularly in ice but not in water.
Step 3
Explain why this drinking water should not be described as pure water.
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Answer
Drinking water cannot be classified as pure water because it contains dissolved solids, specifically ions such as calcium and hydrogen carbonate. Pure water is defined as containing only water molecules without any other substances.
Step 4
State the information from Figure 2 that shows that the drinking water is neutral.
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Answer
The information from Figure 2 that indicates the drinking water is neutral is that it has a pH of 7.
Step 5
Calculate the mass of calcium ions in 250 cm³ of this drinking water.
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Answer
To calculate the mass of calcium ions in 250 cm³ of the drinking water, we use the information that there are 60 mg of calcium ions per 1000 cm³.
Using a proportion: ext{Mass of calcium ions in 250 cm³} = rac{60 ext{ mg}}{1000 ext{ cm³}} imes 250 ext{ cm³} = 15 ext{ mg}
Step 6
State how you know that calcium is a metal from its position in the periodic table.
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Answer
Calcium is known to be a metal because it is located in Group 2 of the periodic table, which typically contains alkaline earth metals. These elements are characterized by their metallic properties such as conductivity and malleability.
