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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
Step 2
Step 3
Explain why this drinking water should not be described as pure water.
Answer
This drinking water should not be described as pure water because it contains various dissolved substances such as calcium ions, sodium ions, and hydrogen carbonate ions. Pure water only consists of water molecules without any other substances, while this sample contains dissolved solids.
Step 4
Step 5
Calculate the mass of calcium ions in 250 cm³ of this drinking water.
Answer
To calculate the mass of calcium ions in 250 cm³ of drinking water, we can use the ratio from Figure 1:
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The mass of calcium ions is 60 mg per 1000 cm³.
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For 250 cm³, the mass can be calculated using the following formula:
ext{Mass} = rac{60 ext{ mg}}{1000 ext{ cm}^3} imes 250 ext{ cm}^3 = 15 ext{ mg}
Thus, the mass of calcium ions in 250 cm³ of this drinking water is 15 mg.
Step 6
State how you know that calcium is a metal from its position in the periodic table.
Answer
Calcium is known to be a metal because it is located on the left side of the periodic table, where metals are generally found. Additionally, calcium is an alkaline earth metal, which is characterized by properties such as being good conductors of heat and electricity, malleability, and the ability to form cations by losing electrons.