I found out this new gases style question, and I'm quite confused Here's the question
A student fills a test tube with 30g of water. He heats up the water so that it begins to boil and collects all of the water vapour produced via a tube into the bung of the test tube. After the beaker has cooled he finds that the mass of the water in the beaker is now 20g. State the mass of the water vapour the student collected. Explain your answer.
As I said I was quite confused about this. How can it end up being 20g when conservation of mass takes place.
I found out this new gases style question, and I'm quite confused Here's the question
A student fills a test tube with 30g of water. He heats up the water so that it begins to boil and collects all of the water vapour produced via a tube into the bung of the test tube. After the beaker has cooled he finds that the mass of the water in the beaker is now 20g. State the mass of the water vapour the student collected. Explain your answer.
As I said I was quite confused about this. How can it end up being 20g when conservation of mass takes place.
Spoiler
He collected 10 g of water vapour... 20 grams is left behind, so 10 grams must be water vapour?
As someone else said, if the question goes onto tell you that the water vapour condenses, they may as well detail how they assembled the apparatus, how they then took it apart, the energy given off by the change of state and I think you get the point; it's not relevant to the question they're asking.
There has to be 10 grams of water since the water being boiled, the pure water vapour travelled into the test tube. So technically 10 grams of pure water vapour was collected and the rest mightn't even be water. Or maybe only 10 grams were collected because the student didn't let the water in the beaker boil completely.