Units in Answer

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AChoudhry_1L
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Joined: Sat Sep 07, 2019 12:17 am

Units in Answer

Postby AChoudhry_1L » Tue Oct 01, 2019 9:44 pm

If a question asks how much of something you will need, should your answer be in grams or moles?

Abigail Menchaca_1H
Posts: 104
Joined: Sat Sep 07, 2019 12:19 am

Re: Units in Answer

Postby Abigail Menchaca_1H » Tue Oct 01, 2019 10:14 pm

Would you mind mentioning what the rest of the problem is?

RKopeikin_3L
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Re: Units in Answer

Postby RKopeikin_3L » Tue Oct 01, 2019 10:22 pm

My guess would be grams but you really need the entire context of the problem to know for sure.

Anna Wu 1H
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Re: Units in Answer

Postby Anna Wu 1H » Tue Oct 01, 2019 10:23 pm

The question usually specifies what unit you should put your answer in, but the general rule is if the givens are in grams, the answer should be in grams, and if the givens are in moles, the answer should be in moles.

Jamie Lee 1F
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Joined: Fri Aug 09, 2019 12:16 am

Re: Units in Answer

Postby Jamie Lee 1F » Tue Oct 01, 2019 10:38 pm

The question will usually tell you what it's looking for. However, it definitely helps to "follow the units". For example, when using dimensional analysis and starting with moles, for example, your answer will usually not end up in moles again and typically you'll be looking for grams.

faithkim1L
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Joined: Fri Aug 09, 2019 12:17 am

Re: Units in Answer

Postby faithkim1L » Tue Oct 01, 2019 10:48 pm

Usually, the problem will ask for the amount in moles or in grams. When this is not the case, I usually read the context of the problem. In labs, you usually just use grams. It's not very likely that you will use moles in the lab.

LBacker_2E
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Re: Units in Answer

Postby LBacker_2E » Tue Oct 01, 2019 11:05 pm

It will depend on the formulas/equations that are used in the problem. For example, if you are working with molarity, and are asked how much of something you need to get a certain M (mol/L) solution, then your answer would be in moles. But if you are asked to find how much excess reactant in a limiting reactant, you would likely need to calculate that in grams.

Ryan Yee 1J
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Joined: Sat Aug 17, 2019 12:16 am

Re: Units in Answer

Postby Ryan Yee 1J » Wed Oct 02, 2019 9:47 am

I'd answer in terms of the given information. However, should the number of grams become very large (say 6-7 digits +) I might convert to kilograms. Moles should always be left either as is, or in scientific notation in my opinion.

Ryan Juncker 3D
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Joined: Wed Sep 18, 2019 12:18 am

Re: Units in Answer

Postby Ryan Juncker 3D » Wed Oct 02, 2019 9:51 am

It most likely depends on the specific problem, but we were told in discussion today that the general order would be to convert from grams to moles in order to work out the problem; then convert back from moles to grams to show your final answer. The example we used this on today was finding how much carbon dioxide you exhale from taking a 1.35g pill of Salicylic Acid that is 15% SA by weight.

Sally kim 4F
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Re: Units in Answer

Postby Sally kim 4F » Wed Oct 02, 2019 11:12 pm

Sometimes it will be in grams, sometimes it will be in moles. It varies depending on what the question is asking. It should be pretty clear in the problem what they are specifically looking for, so don't worry too much!

erica thompson 4I
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Joined: Wed Sep 18, 2019 12:21 am

Re: Units in Answer

Postby erica thompson 4I » Thu Oct 03, 2019 12:01 am

Like what many people said above, it depends what the problem is asking for. If the problem was asking you to solve for the mass, the answer would be in grams. I believe in lecture today he said that the SI fundamental units were:

- mass = kilograms
- length = meters
- time = seconds

Doreen Liu 4D
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Joined: Wed Sep 11, 2019 12:17 am

Re: Units in Answer

Postby Doreen Liu 4D » Thu Oct 03, 2019 8:55 am

You should always answer with the unit that the question is asking. If it began with moles and asked how many moles are in the end, then keep/convert answer into moles, but if it began with grams and asked for the mass, then keep/convert answer into mass.

Luyan Zhang - 2D
Posts: 103
Joined: Sat Jul 20, 2019 12:16 am

Re: Units in Answer

Postby Luyan Zhang - 2D » Thu Oct 03, 2019 9:30 am

If the question asks for "mass", you should put grams

Gabriel Ordonez 2K
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Joined: Sat Jul 20, 2019 12:15 am

Re: Units in Answer

Postby Gabriel Ordonez 2K » Thu Oct 03, 2019 11:17 am

Usually, the question will state the required units it wants. Either, it will say, "What is the amount(in moles)..." or "How many grams of x atoms or molecules will be created from x and y," and so on. Please read the question itself and any background passage that precedes it, and you should be able to answer the question to the fullest.

alexfwang3g
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Re: Units in Answer

Postby alexfwang3g » Thu Oct 03, 2019 11:30 am

Should be specified in the question.

Laurie Tan 4C
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Joined: Thu Jul 11, 2019 12:17 am

Re: Units in Answer

Postby Laurie Tan 4C » Fri Oct 04, 2019 1:39 am

The wording in the question should give hints on what units the answer should be in. Since the questions vary so much, it's difficult to pick one unit for all of your answers, so it's best to check what the question is asking for. :)

ValerieChavarin 4F
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Joined: Wed Sep 18, 2019 12:18 am

Re: Units in Answer

Postby ValerieChavarin 4F » Fri Oct 04, 2019 1:32 pm

The question usually specifies which unit is preferred in the answer. If there is a certain question you are referencing, try posting it verbatim, in order to clear up the confusion.

Max Madrzyk Dis 4G
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Joined: Wed Sep 18, 2019 12:21 am

Re: Units in Answer

Postby Max Madrzyk Dis 4G » Fri Oct 04, 2019 1:39 pm

I think you have to look at what the question is asking for in order to determine if the answer should be in grams or moles.

Megan_1F
Posts: 49
Joined: Thu Jul 25, 2019 12:16 am

Re: Units in Answer

Postby Megan_1F » Fri Oct 04, 2019 2:44 pm

Regarding Sig Figs in our final answer, should we be using the amount of sig figs that is given to us in the problem and work our molar mass around that amount of sig figs?


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