sapling hw #7
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sapling hw #7
Hi guys!
Im having trouble with #7 on the hw for this week: A solution of CaCl2 in water forms a mixture that is 32.5% calcium chloride by mass. If the total mass of the mixture is 590.1 g, what masses of CaCl2 and water were used?
Can someone explain how they approach a problem like this/what would their first step be
thanks!
Im having trouble with #7 on the hw for this week: A solution of CaCl2 in water forms a mixture that is 32.5% calcium chloride by mass. If the total mass of the mixture is 590.1 g, what masses of CaCl2 and water were used?
Can someone explain how they approach a problem like this/what would their first step be
thanks!

 Posts: 87
 Joined: Wed Sep 30, 2020 9:55 pm
Re: sapling hw #7
Hello!
So in order to find the mass of CaCl2 you are going to have to multiply the 36.5% of calcium chloride by the total mass of the mixture, 903.4 g:
mass CaCl2= 903.4g x 36.5% = 329.74 g CaCl2
Second, in order to find the mass of water used you are going to have to subtract the mass of CaCl2 from the total mass, 903.4g:
mass of H2O= 903.4g  329.74g= 573.99 g of H2O
Hope this helps!
So in order to find the mass of CaCl2 you are going to have to multiply the 36.5% of calcium chloride by the total mass of the mixture, 903.4 g:
mass CaCl2= 903.4g x 36.5% = 329.74 g CaCl2
Second, in order to find the mass of water used you are going to have to subtract the mass of CaCl2 from the total mass, 903.4g:
mass of H2O= 903.4g  329.74g= 573.99 g of H2O
Hope this helps!

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 Joined: Wed Sep 30, 2020 9:49 pm
 Been upvoted: 1 time
Re: sapling hw #7
Hello!
For this problem the solution is easier than you would think. To find the mass of calcium chloride you multiply .325 with 590.1 g (giving you about 191.78 g), as you know that calcium chloride would constitute 32.5% of the total mass of this mixture. Then to find the mass of the water, you would subtract the product you calculated earlier from the total mass of 590.1 g ( so 590.1  191.78 = about 398.32 g water).
For this problem the solution is easier than you would think. To find the mass of calcium chloride you multiply .325 with 590.1 g (giving you about 191.78 g), as you know that calcium chloride would constitute 32.5% of the total mass of this mixture. Then to find the mass of the water, you would subtract the product you calculated earlier from the total mass of 590.1 g ( so 590.1  191.78 = about 398.32 g water).

 Posts: 91
 Joined: Wed Sep 30, 2020 9:31 pm
Re: sapling hw #7
Hey! This problem is actually easier than you might think. I know I was overthinking it before I realized that it's just multiplication and subtraction.
The first thing you have to do is figure out the mass of calcium chloride. It is given than the mixture contains 32.5% calcium chloride, so all you do here is multiply the total mass of mixture (590.1 g) by 0.325. When you do this, you find that there is 191.8 g of calcium chloride.
Then you subtract the mass of calcium chloride (191.8 g) from the mass of the total mixture (590.1 g) to find the mass of water. When you do this, you find that there is 398.3 g of water.
Hope this helps!
The first thing you have to do is figure out the mass of calcium chloride. It is given than the mixture contains 32.5% calcium chloride, so all you do here is multiply the total mass of mixture (590.1 g) by 0.325. When you do this, you find that there is 191.8 g of calcium chloride.
Then you subtract the mass of calcium chloride (191.8 g) from the mass of the total mixture (590.1 g) to find the mass of water. When you do this, you find that there is 398.3 g of water.
Hope this helps!

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 Joined: Wed Sep 30, 2020 9:36 pm
Re: sapling hw #7
Hi! For this problem, it says that 32.0% of the mixture is calcium chloride and the total mass of the mixture is 310.1 g with the water. First, you have to find the amount of calcium chloride in the solution so you would multiply 310.1 g by .32 to get that the mass of CaCl2 is 99.2 g. The remainder of the solution would be the water so you would just subtract that value from the total mass. Therefore, 310.1 g 99.2 g = 210.9 g of water.

 Posts: 86
 Joined: Wed Sep 30, 2020 9:45 pm
Re: sapling hw #7
Hello!
For this problem, it is a matter of converting the percentage of calcium chloride, 32.5%, into a decimal number, 0.325. Once you have this, you should be set to multiply the total mass by this number to determine the mass of calcium chloride. For the final step, you would have to use the given total mass and subtract the mass of calcium chloride to find the mass of water, the remaining difference.
For this problem, it is a matter of converting the percentage of calcium chloride, 32.5%, into a decimal number, 0.325. Once you have this, you should be set to multiply the total mass by this number to determine the mass of calcium chloride. For the final step, you would have to use the given total mass and subtract the mass of calcium chloride to find the mass of water, the remaining difference.

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 Joined: Fri Oct 02, 2020 12:16 am
Re: sapling hw #7
After reading some of the replies, I'm afraid I have a silly question.
People are saying to "multiply 0.325 with 590.1g" but my question is what they did to get 0.325 and why.
Thank you!
People are saying to "multiply 0.325 with 590.1g" but my question is what they did to get 0.325 and why.
Thank you!

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 Joined: Wed Sep 30, 2020 9:47 pm
Re: sapling hw #7
Gicelle Rubin 1E wrote:After reading some of the replies, I'm afraid I have a silly question.
People are saying to "multiply 0.325 with 590.1g" but my question is what they did to get 0.325 and why.
Thank you!
They got .325 from the percentage of calcium chloride (32.5%). You would move the decimal point on the percentage two spots to the left, making it 0.325, and it just makes it easier to multiply the percentage with 590.1 g.

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 Joined: Wed Sep 30, 2020 10:04 pm
Re: sapling hw #7
Gicelle Rubin 1E wrote:After reading some of the replies, I'm afraid I have a silly question.
People are saying to "multiply 0.325 with 590.1g" but my question is what they did to get 0.325 and why.
Thank you!
Don't be afraid! Because I too was wondering the same thing. Thank you for asking before I did! We're all in this together.

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Re: sapling hw #7
Well logically, if you add the mass of the CaCl2 and the water, you should get the mass of the total solution. And, CaCl2 represents 32.5% then the water must represent 67.5% because water+CaCl2=100%. So if you multiply the total mass by the .325 and .675 to find the masses of the CaCl2 and water respectivly.

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 Joined: Wed Sep 30, 2020 9:31 pm
Re: sapling hw #7
The mass of CaCl2 is going to be 32.5% of the total mass, so we just multiply the total mass by 0.325.
There are a couple ways you can do the next part of the problem, but the easiest is to subtract the mass of CaCl2 from the total mass, because we know that everything that isn't CaCl2 is water.
There are a couple ways you can do the next part of the problem, but the easiest is to subtract the mass of CaCl2 from the total mass, because we know that everything that isn't CaCl2 is water.
Re: sapling hw #7
The wording of this problem might make it seem more difficult than it really is, but when it comes down to it you just have to multiply. The only real conversion is taking the percentage and making that into a decimal, .325. Then, you are going to want to multiply this decimal by the total mass in order to find the amount that is calcium chloride. You can then just subtract the product from the total mass to find the remaining, which is all water.

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Re: sapling hw #7
The way I looked at it is if the mixture is 32.5% calcium chloride by mass, then the other 67.5% of the solution must be water. We can multiply the total mass 590.1 by .675 to get the mass of the water in the solution. 590.1 x .675 = 398.3175 grams H2O

 Posts: 92
 Joined: Wed Sep 30, 2020 9:38 pm
Re: sapling hw #7
Here is how I would solve it,
Since there is 32.5% of calcium chloride in the mixture, I would just multiply .325 with the total mixture which is 590.1 and I got 191.78g of CaCl2. I subtract 191.78g of CaCl2 from 590.1g of total mixture to get the grams of water used and I got 398.32g of water.
Since there is 32.5% of calcium chloride in the mixture, I would just multiply .325 with the total mixture which is 590.1 and I got 191.78g of CaCl2. I subtract 191.78g of CaCl2 from 590.1g of total mixture to get the grams of water used and I got 398.32g of water.

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 Posts: 91
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Re: sapling hw #7
I approached this problem by imagining the calcium chloride in grams. So if your calcium chloride was 32.5% I thought of it as 32.5 g out of 100g. Then I set up two fractions with 32.5 over 100 equaling to x over the total mass of the mixture. I cross multiplied and 100x equaling the product of the total mass and the 32.5g. I then just solved for x by dividing. This is the mass of calcium chloride. To get the mass of water just subtract that number from the original total mass of the mixture.

 Posts: 81
 Joined: Wed Sep 30, 2020 10:01 pm
Re: sapling hw #7
Hey!
For this problem, you know that 32.5% of the sln. is calcium chloride. Therefore, the other 67.5% of the sln. must be H20. If the sln. is 590.1g, then 32.5% of 590.1 is 191.78g of CaCl2. Then, after subtracting that mass from 590.1, you get the grams of H20 that make up the sln.
For this problem, you know that 32.5% of the sln. is calcium chloride. Therefore, the other 67.5% of the sln. must be H20. If the sln. is 590.1g, then 32.5% of 590.1 is 191.78g of CaCl2. Then, after subtracting that mass from 590.1, you get the grams of H20 that make up the sln.

 Posts: 101
 Joined: Wed Sep 30, 2020 9:45 pm
Re: sapling hw #7
This question is alot simpler than you think! To start you multiple the percent of CaCl by the total mass. That will you give you the grams of CaCl in the solution. Next just subtract the mass of the CaCl from the total mass of solution, which will give you the mass of the water. And thats it! hoped it helped
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