Stuck on Sapling HW

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Janna Shakiba
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Joined: Wed Sep 30, 2020 10:02 pm

Stuck on Sapling HW

Postby Janna Shakiba » Sat Oct 10, 2020 12:36 pm

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?

Sandra Kim 2B
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Joined: Wed Sep 30, 2020 9:50 pm

Re: Stuck on Sapling HW

Postby Sandra Kim 2B » Sat Oct 10, 2020 12:44 pm

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 :)

Sukhkiran Kaur 3I
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Re: Stuck on Sapling HW

Postby Sukhkiran Kaur 3I » Sat Oct 10, 2020 1:40 pm

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.

Gicelle Rubin 1E
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Re: Stuck on Sapling HW

Postby Gicelle Rubin 1E » Sat Oct 10, 2020 2:25 pm

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!

Nicolette Simoni 3L
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Re: Stuck on Sapling HW

Postby Nicolette Simoni 3L » Sat Oct 10, 2020 2:39 pm

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! :)

Janna Shakiba
Posts: 91
Joined: Wed Sep 30, 2020 10:02 pm

Re: Stuck on Sapling HW

Postby Janna Shakiba » Sun Oct 11, 2020 12:49 pm

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!

Jose Miguel Conste 3H
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Joined: Sat Oct 03, 2020 12:15 am

Re: Stuck on Sapling HW

Postby Jose Miguel Conste 3H » Sun Oct 11, 2020 9:23 pm

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.

Nick Saeedi 1I
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Re: Stuck on Sapling HW

Postby Nick Saeedi 1I » Sun Oct 11, 2020 10:24 pm

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.

905579227
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Joined: Wed Sep 30, 2020 10:01 pm

Re: Stuck on Sapling HW

Postby 905579227 » Sun Oct 18, 2020 11:45 pm

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.

Leyla Anwar 3B
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Re: Stuck on Sapling HW

Postby Leyla Anwar 3B » Sun Oct 25, 2020 3:50 pm

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.

Kaiya_PT_1H
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Re: Stuck on Sapling HW

Postby Kaiya_PT_1H » Sun Oct 25, 2020 10:08 pm

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!

Andrew Yoon 3L
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Joined: Wed Sep 30, 2020 9:36 pm

Re: Stuck on Sapling HW

Postby Andrew Yoon 3L » Sun Oct 25, 2020 10:16 pm

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.

105618850
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Joined: Wed Sep 30, 2020 9:38 pm

Re: Stuck on Sapling HW

Postby 105618850 » Fri Dec 04, 2020 11:12 am

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.

Katie Phan 1K
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Joined: Wed Sep 30, 2020 9:55 pm

Re: Stuck on Sapling HW

Postby Katie Phan 1K » Fri Dec 04, 2020 7:02 pm

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 audio-visual units about molarity/dilution.

Morgan Gee 3B
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Joined: Wed Sep 30, 2020 9:48 pm

Re: Stuck on Sapling HW

Postby Morgan Gee 3B » Sat Dec 05, 2020 6:08 pm

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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