SI Base Unit Kg

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Brendan Duong 1I
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Joined: Wed Sep 30, 2020 10:07 pm

SI Base Unit Kg

Postby Brendan Duong 1I » Thu Oct 08, 2020 12:35 am

If Kg is the base unit we use in chemistry (as opposed to grams which seems weird to me), then does that mean all future formulas we use involving mass should be with kg? For example Ek=0.5me-*ve-^2 where me- is in kg?

Andrew Jubintoro 3J
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Re: SI Base Unit Kg

Postby Andrew Jubintoro 3J » Thu Oct 08, 2020 1:43 am

I think that it really depends on what other units are involved in the formula.
For example kinetic energy has the unit Joules or so it makes sense to use kilograms when calculating for kinetic energy.
On the other hand if you are given the mass of a substance in grams and were asked to calculate its amount in moles, then there is no need to convert the mass to kilograms because the molar mass you would use will be in

Becca Nelson 3F
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Re: SI Base Unit Kg

Postby Becca Nelson 3F » Thu Oct 08, 2020 10:26 am

As a general rule of them look at the unit in the equations you are using. While kilograms is the SI unit, there are many lab instances where using grams is preferred. Just make sure to always check the equation and what it requires (g or kg) and to see what units the final answer asks for and do you math accordingly.

Zainab Jamali 1H
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Joined: Wed Sep 30, 2020 9:54 pm

Re: SI Base Unit Kg

Postby Zainab Jamali 1H » Thu Oct 08, 2020 11:04 am

Becca Nelson 1J wrote:As a general rule of them look at the unit in the equations you are using. While kilograms is the SI unit, there are many lab instances where using grams is preferred. Just make sure to always check the equation and what it requires (g or kg) and to see what units the final answer asks for and do you math accordingly.


This is a good point! Often times, even though m^3 is the SI unit for volume a lot of chemistry problems will give values or ask for answers in mL or L.
Last edited by Zainab Jamali 1H on Thu Oct 08, 2020 11:02 pm, edited 1 time in total.

OwenSumter_2F
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Re: SI Base Unit Kg

Postby OwenSumter_2F » Thu Oct 08, 2020 11:39 am

Also, using g or mg or any other unit like that is perfectly fine, it is just a convenience for us. It would be very annoying having to write 3.2x10-6kg in every lab working with small amounts.

Grace_Remphrey_2J
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Re: SI Base Unit Kg

Postby Grace_Remphrey_2J » Thu Oct 08, 2020 12:36 pm

I would recommend using the units that the initial problem uses unless the problem states for you to change the units in your final answer. Hope this helps!


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