If liquid water is cooled below 0°C it turns into the solid, ice - Edexcel - GCSE Chemistry Combined Science - Question 1 - 2021 - Paper 1
Question 1
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 Combined Science - Question 1 - 2021 - Paper 1
Step 1
Give the name for the change of state from liquid to solid.
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Answer
The name for the change of state from liquid to solid is freezing.
Step 2
Place ticks in boxes by the two statements that are correct.
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Answer
the molecules move faster in water than in ice ✔
the molecules have more energy in ice than in water ✔
Step 3
Explain why this drinking water should not be described as pure water.
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Answer
This drinking water should not be described as pure water because it contains dissolved solids such as calcium ions, sodium ions, and hydrogen carbonate ions. Pure water consists only of H₂O molecules without any impurities.
Step 4
State the information from Figure 1 that shows that the drinking water is neutral.
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Answer
The pH of water is 7, indicating that the drinking water is neutral.
Step 5
Calculate the mass of calcium ions in 250 cm³ of this drinking water.
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Answer
To find the mass of calcium ions, we use the concentration from Figure 1. The concentration is 60 mg per 1000 cm³.
Using the formula:
extmass=extconcentrationimesextvolume
We find the mass in 250 cm³ as follows:
extmass=60extmg/1000cm3imes250extcm3=15extmg
Thus, the mass of calcium ions is 15 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 as it is located in Group 2 of the periodic table, which is known for alkaline earth metals, exhibiting typical metallic properties such as conductivity and malleability.
