m1v1=m2v2 or m1v2=m2v1

[arpitpatel86]

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when do u use M1V1=M2V2 and when do u use M1V2=M2V1......i never know when to use which one

 

[joonkimdds]

I've never heard of M1V2 =M2V1...hm...
M1V1=M2V2 is used if u wanna drink coffee 🙂
u put coffee mixture in H2O and make coffee right? (I m not sure...i never had coffee in my life).
so now the the water is polluted with coffee mixture 😀
so u compare before u put the coffe into water and after.

 

[nixon13]

I think you meant m1v1=m2v2 and n1v1=n2v2. To answer your question, when you are comparing an acid and a base with equivalent amounts of H and OH (ex. HCl and NaOH, notice how there is 1 H in HCl and 1 OH in NaOH) then you use m1v1=m2v2. Use normality n1v1=n2v2 when you have an acid and a base with unequal amount of H and OH (ex H2SO4 and NaOH, notice how H2SO4 has 2 H and NaOH again has 1 OH). To get normality you simply multiply the number of H or OH by 2. (ex. H2SO4 has normality of 4, H3PO4 has normality of 6 etc...hope that helps, someone correct me if im wrong but its worked for me on every problem on acid/base.

 

[arpitpatel86]

know my question was correct on destroyer number 170 they did M1V2=M2V1 instead of m1v1=m2v2
the question was An unknown mineral has density of 5g/cm^3. If a 2.0 cm^3 sample has a mass of 10g. what is the mass of 9 cm^3 sample?
A.30 g
b 45g
c.50g
d.60g
e 18g

the solution was D=M/V so m1/v1=m2/v2 which is essentially the same thingis M1v2=m2v1 why did they do this instead of m1v1=m2v2 when do u use which one?

 

[250rsavage]

They are saying that the densities are the same so D=M1/V1 is equal to D=M2/V2 = M1/V1=M2/V2 or if you want M1V2=M2V1 but that is not important for this problem. This is just a proportional problem, you are making this harder than it really is

 

[bigstix808]

one is for comparing densities (D=M/V) and the other is for figuring out dilutions.

don't try and memorize m1v2=m2v1 as that is not practical in everyday general chemistry practice. you need to gather the concepts associated with that particular problem and understand WHY you even set the two densities equal to each other in the first place.