G.Chem help!

[Clovers]

I don't know why gchem is so hard for me. This is supposed to be an easy question on Achiever but I don't understand how to do it.

How many millimeter of 3.0M H2SO4 are required to neutralize 30.0ml of 4.0M NaOH?

I thought you use M1V1=M2V2. I used that and got 40 which is the incorrent answer.

This is how they did it on Achiever,

0.5 x 30(4.0)/1000 x 1000/3.0 = 20 ml

Where did the 0.5 come from?

Thanks all!

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[Lily-VA]

I don't know why gchem is so hard for me. This is supposed to be an easy question on Achiever but I don't understand how to do it.

How many millimeter of 3.0M H2SO4 are required to neutralize 30.0ml of 4.0M NaOH?

I thought you use M1V1=M2V2. I used that and got 40 which is the incorrent answer.

This is how they did it on Achiever,

0.5 x 30(4.0)/1000 x 1000/3.0 = 20 ml

Where did the 0.5 come from?

Thanks all!

I didn't know they have solutions in Achiever, haha (got it yesterday)
Well, I received a lowest possible grade in GC on first set, but I think I know how to solve it..let me see..

1) H2SO4 + 2 NaOH-> 2 H2O(l) + 2 Na+(aq) + SO4 2-(aq)

2)find moles od NaOH: x/30ml = 4M NaOH so..120mole NaOH

3) find Volume of H2SO4 using the 2) answer b/c neutralizing:
120mole/Vol= 3M H2SO4, Vol of H2So4 is 40ml but we have to think of molar ratio...

4) when 2 moles of NaOH is used only 1 mole of H2SO4 is used, right?
Then you need to divide by 2 because we used one mole of NaOH in the beginning (sorry I can't any succinct about explanation)

Basically you have to look at the balanced equation.

(I got this prob worng anyways^ ^ Now I can get it!)

BTW, how can you view the solution in Achiever??

 

[Clovers]

I didn't know they have solutions in Achiever, haha (got it yesterday)
Well, I received a lowest possible grade in GC on first set, but I think I know how to solve it..let me see..

1) H2SO4 + 2 NaOH-> 2 H2O(l) + 2 Na+(aq) + SO4 2-(aq)

2)find moles od NaOH: x/30ml = 4M NaOH so..120mole NaOH

3) find Volume of H2SO4 using the 2) answer b/c neutralizing:
120mole/Vol= 3M H2SO4, Vol of H2So4 is 40ml but we have to think of molar ratio...

4) when 2 moles of NaOH is used only 1 mole of H2SO4 is used, right?
Then you need to divide by 2 because we used one mole of NaOH in the beginning (sorry I can't any succinct about explanation)

Basically you have to look at the balanced equation.

(I got this prob worng anyways^ ^ Now I can get it!)

BTW, how can you view the solution in Achiever??

Hey, thanks! Do you know a shortcut to this? To view answers just click on the test you've done already and there will be a button that saids "show solution." Good luck and thanks!

 

[Lily-VA]

think short cut might be what they have used...
But I usually follow my thoughts even if it's long..stubborn

Thanks for the tip on achiever!

 

[haavoc]

Hi,

Sulfuric acid has to 2 H+ equivlents and sodium hydroxide has 1 equivalent of OH-.

Here's what I do:

a = acid
b = base
n = H+ equivalents
m = OH- equivalents

n*Ma*Va = m*Mb*Vb

In this case:

2*3*Va = 1*4*30

Va = (4*30) / (2*3)

Va = 20 mL H2SO4 needed