A student bubbles carbon dioxide into limewater that holds 1.85 g of calcium hydroxide (74.09…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A student bubbles carbon dioxide into limewater that holds of calcium hydroxide (). First the water turns milky, and with more gas it clears. Find the largest mass of calcium carbonate () that forms. Find the volume of carbon dioxide, at and , that has been used when the milkiness is greatest. Find the total volume of carbon dioxide that has been used when the water is clear again, and calcium hydrogencarbonate is the only product. Take .
Need a reminder? The key ideaShow
A gas at and has a molar volume of . Calcium hydroxide takes up carbon dioxide mole for mole: . When a mixture loses mass on heating, the loss of each solid is its fraction of CO (and water) times its mass.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Moles. of calcium hydroxide.
Step 2. Calcium carbonate. One mole forms from each mole: .
Step 3. First volume of gas. .
Step 4. The second reaction. Each mole of calcium carbonate takes another mole of CO. So the total is .
Answer: , and .
Check. The overall equation is , which uses 2 mol of CO for each mole of hydroxide. This agrees.
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