Stuck on Sapling HW
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Stuck on Sapling HW
If 3.39 g of CuNO3 is dissolved in water to make a 0.580 M solution, what is the volume of the solution in milliliters?

 Posts: 94
 Joined: Wed Sep 30, 2020 9:50 pm
Re: Stuck on Sapling HW
like the hint on the problem suggests, you need to find CuNO3 in moles, so you first have to get the molar mass of the compound and convert to moles with the molar mass and the given mass. Then, you take the formula M=n/V but isolate V. Then, you plug in everything you have to get V which is in liters so then you convert that answer to mL! Hope this helps :)

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 Joined: Wed Sep 30, 2020 10:03 pm
Re: Stuck on Sapling HW
In order to solve this, you should first convert the CuNO3 to moles using the molar mass. Then plug your value into the formula V=M/n to get the volume in L, and convert that into mL.

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 Joined: Fri Oct 02, 2020 12:16 am
Re: Stuck on Sapling HW
I was also confused at first but, you must convert CuNO3 into moles. After you find that number, use the formula: (v=m/n). Remember that the equation gives you the answer in liters to make sure to convert it to milliliters!

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Re: Stuck on Sapling HW
Hi!
First you must convert what you have for CuNO3 into moles. Then you would have to follow the formula V=n/m. You would have to change the formula to M=n/V. Then, since what you have for volume is in liters, you must divide your volume by 1000 to convert it to milliliters and get your final answer!
Good chemistry is happening! :)
First you must convert what you have for CuNO3 into moles. Then you would have to follow the formula V=n/m. You would have to change the formula to M=n/V. Then, since what you have for volume is in liters, you must divide your volume by 1000 to convert it to milliliters and get your final answer!
Good chemistry is happening! :)

 Posts: 91
 Joined: Wed Sep 30, 2020 10:02 pm
Re: Stuck on Sapling HW
Thank you so much everyone!
The problem was actually that I was using the molar mass of Cu(NO3)2 instead of CuNO3 which was why I kept getting the wrong answer. Note to self and everyone else: double check your compound formulas!
The problem was actually that I was using the molar mass of Cu(NO3)2 instead of CuNO3 which was why I kept getting the wrong answer. Note to self and everyone else: double check your compound formulas!

 Posts: 91
 Joined: Sat Oct 03, 2020 12:15 am
Re: Stuck on Sapling HW
First you would like to find out how many moles the total grams have, then conver that to Liters using the molarity given, afterwards then convert Liters to militers and you should be able to get the answer.

 Posts: 107
 Joined: Wed Sep 30, 2020 9:39 pm
Re: Stuck on Sapling HW
I first converted grams of CuNO3 to moles then I used the equation M=n/V and rearranged it for V. Just plug in the values now and you should get the correct answer.
Re: Stuck on Sapling HW
Hey everyone, I was wondering if anyone on here could tutor me on molarity, i cant seem to undestand it all the way through. If you can tutor me please reply and ill frind a way to conatact you.

 Posts: 90
 Joined: Wed Sep 30, 2020 10:03 pm
Re: Stuck on Sapling HW
Why do we need to convert from g to moles here? Does the molarity equation need to have the compound in moles instead of grams? I just don't know the reasoning for needing moles. Thanks.

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 Joined: Wed Sep 30, 2020 10:07 pm
Re: Stuck on Sapling HW
Leyla Anwar 1C wrote:Why do we need to convert from g to moles here? Does the molarity equation need to have the compound in moles instead of grams? I just don't know the reasoning for needing moles. Thanks.
We have to convert from grams to moles because the unit for molarity is moles per liter. The equation M = n/V uses moles for n, liters for V, and molar (moles/liter) for M, which makes sense because n/V is just moles in the solution divided by liters of solution!

 Posts: 92
 Joined: Wed Sep 30, 2020 9:36 pm
Re: Stuck on Sapling HW
The first step is to convert 3.39g of CuNO3 into moles. You can do this using the molar mass of CuNO3. Once you have converted the mass to moles, use the molarity equation (M = n/v) to solve for the volume. Make sure to convert to milliliters.
Re: Stuck on Sapling HW
First you would need to convert CuNO3 into moles and plug it into the equation M=n/v as well as the given molarity. You would then arrive at an answer in L and therefore, would need to convert it into mL.

 Posts: 93
 Joined: Wed Sep 30, 2020 9:55 pm
Re: Stuck on Sapling HW
905579227 wrote:Hey everyone, I was wondering if anyone on here could tutor me on molarity, i cant seem to undestand it all the way through. If you can tutor me please reply and ill frind a way to conatact you.
Watch the videos that Lavelle has up on his website! And do the audiovisual units about molarity/dilution.

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 Joined: Wed Sep 30, 2020 9:48 pm
Re: Stuck on Sapling HW
Understanding the units for this question is extremely important. M is the unit mol/liter and is often referred to as concentration. We are given grams and concentration, but we still need mols and liters. To find the mols, we use the molar mass of CuNO3 which is 125.55 g/mol (from the periodic table). Using the molar mass, we calculate the mols of CuNO3 to be 0.0270 mols. We can now create an equation that states 0.0270 mols/x = 0.580 M. Using algebra, we solve for x (which is liters of solution) and find it to be 0.0466 L. We want to find mL, so multiply by 1000 and get 46.6 mL of solution.
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