The problem is "A solution of CaCl2 in water forms a mixture that is 39.5% calcium chloride by mass. If the total mass of the mixture is 577.0 g, what masses of CaCl2 and water were used?"
I guess my question is: I don't really know how to navigate this problem and start. How do I find what mass was used originally? Is it as simple as subtracting from the total mass or are there more steps that I have to complete?
Homework Week 1 Question 7
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Re: Homework Week 1 Question 7
since you know the percent of calcium chloride and the total mass of the mixture, you can find the exact mass of the calcium chloride. Then you subtract that answer from the total mass to get the mass of the water used.
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Re: Homework Week 1 Question 7
I think a good place to start is figuring out what you have and need. You're given the percent composition of the CaCl2, and the entire mass of the solution. You can figure out the percent composition of the water, since you know there are only two reactants. Then you can find what you need, which is the mass of water.
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Re: Homework Week 1 Question 7
Hi Maggie!
I believe what you would do would be to break this problem up first. We know the total mass of the mixture of calcium chloride and water as well as the percentage of the CaCl2, so we would multiply the percentage as a decimal by the total grams (.395)(577g) to get the grams of CaCl2. Then from there, you could find the mass of the remaining water by subtracting the answer from the total mass because I believe it is a mass percentage type of problem.
Hope this helps and anyone else feel free to correct me if I made an error - this was my thought process.
I believe what you would do would be to break this problem up first. We know the total mass of the mixture of calcium chloride and water as well as the percentage of the CaCl2, so we would multiply the percentage as a decimal by the total grams (.395)(577g) to get the grams of CaCl2. Then from there, you could find the mass of the remaining water by subtracting the answer from the total mass because I believe it is a mass percentage type of problem.
Hope this helps and anyone else feel free to correct me if I made an error - this was my thought process.
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Re: Homework Week 1 Question 7
Hello!
It definitely appears complicated but if we break it down it's quite easy to navigate. You can find the mass of CaCl2 by multiplying the percentage of calcium chloride given by the total mass of the mixture, after that you can use algebra and take the total mass given - the fraction of total mass to find the weight of water in the mixture!
It definitely appears complicated but if we break it down it's quite easy to navigate. You can find the mass of CaCl2 by multiplying the percentage of calcium chloride given by the total mass of the mixture, after that you can use algebra and take the total mass given - the fraction of total mass to find the weight of water in the mixture!
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Re: Homework Week 1 Question 7
Because the formed mixture is 38.5% calcium chloride by mass and the total mass of the mixture is 252.4 grams, all you have to do is multiply the percentage and the total mass to find the mass of the CaCl2 (which will be in grams). Once you've found that, you can subtract that mass from the total mass of the mixture to find the remaining mass which is the mass of the water in the mixture.
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Re: Homework Week 1 Question 7
For this question, I set up an equation first to find the mass of calcium chloride. Since we know it is 39.5% of the total mass of 577.0 g, this is the equation I used:
x/577.0 x 100 = 39.5
After solving, you would know that the mass of calcium chloride is 227.9 grams.
After that, you can just subtract this mass from the total, which would give you the mass of water:
577.0 - 227.9 = 349.1 grams of water
I'm not sure if there is a method that's quicker though, but this was how I found my answer
x/577.0 x 100 = 39.5
After solving, you would know that the mass of calcium chloride is 227.9 grams.
After that, you can just subtract this mass from the total, which would give you the mass of water:
577.0 - 227.9 = 349.1 grams of water
I'm not sure if there is a method that's quicker though, but this was how I found my answer
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