Is normality on the DAT?

[predentlove]

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Hi, how would I approach this normality problem?
If 49 grams of H2SO4 is mixed with enough H2O to make 500 mL of solution, what is the normality?

Thank youuu! 🙂 😍

 

[AlbinoPolarBear]

Hi, how would I approach this normality problem?
If 49 grams of H2SO4 is mixed with enough H2O to make 500 mL of solution, what is the normality?

Thank youuu! 🙂 😍

Yeah, this is fair game.

Find molarity first (concentration), then multiply by 2 as there are 2 moles of H+ for every mole of H2SO4.

Given:
Volume = 0.5 L
mass = 49 g
MW = 2+32+64 = 98 g/mol

concentration = moles/Volume
and
moles = mass/MW

therefore

conc = mass/(vol*MW)
conc = 49/(0.5*98)
conc = 1 M

since we know there are 2 moles of H+ for every mole of H2SO4.

normality = conc * 2
normality = 2 N

 

[LetsGo2DSchool]

Albino will teach you over skype as long as you promise to blow him a kiss.

 

[AlbinoPolarBear]

Albino will teach you over skype as long as you promise to blow him a kiss.

If anyone wants to get tutoring over skype, they have to promise to keep their clothes on. 👍

 

[LetsGo2DSchool]

If anyone wants to get tutoring over skype, they have to promise to keep their clothes on. 👍

That means he wants you to keep them on before providing a strip tease.

 

[predentlove]

Lol what is going onnn!

Thanks for your help!! You guys are too smart!!

 

[predentlove]

😵

 

[predentlove]

P.S.
I have another question...
I tried using Change in T = i m k
but i didn't get the answer... :''''(

A 1.50 gram sample of urea is dissolved in 105 grams of water and produces a solution that boils at 100.12 degrees C. From this data, what is the molecular mass of urea?

 

[AlbinoPolarBear]

P.S. I tried using Change in T = i m k
but i didn't get the answer... :''''(

A 1.50 gram sample of urea is dissolved in 105 grams of water and produces a solution that boils at 100.12 degrees C. From this data, what is the molecular mass of urea?

Given:
MW of Urea: ?
Mass of urea: 1.50 g
dT = 0.12
mass of water: 105g = 0.105 kg
Kb of water ~ 0.5 (should be given..)
i = 1, as urea does not dissociate into ions

Equations:
1) dT = Kb*molality*i

2) molality = moles urea/mass water
3) moles urea = mass urea/MW urea

Combining 2+3, we get:
4)molality = mass urea / (mass water)*(MW urea)

Combining 1+4, we get:

dT = Kb*molality*i
dT = (Kb*massU*i) / (massW*MW)
MW = (Kb*massU*i) / (massW*dT)
MW = (0.5*1.5*1 / (0.105*0.12)
MW = 0.75/ 0.0126
MW ~ 60

Hope you had a calc to help u out with this, if you did it fast (with rounding, you would get something around 75 g/mol, which is pretty close to the actual answer), but I guess it will depend there what are the answer choices.

eg.
MW = (0.5*1.5*1) / (0.1*0.1)
MW = 0.75/0.01
MW = 75

From rounding, we decreased the denominator, so we know the real answer should be less than 75.

 

[LetsGo2DSchool]

P.S.
I have another question...
I tried using Change in T = i m k
but i didn't get the answer... :''''(

A 1.50 gram sample of urea is dissolved in 105 grams of water and produces a solution that boils at 100.12 degrees C. From this data, what is the molecular mass of urea?

Isn't urea the main component in urine? So why would anyone in this world make a solution of piss and boil it? It just doesn't make sense 😕

 

[AlbinoPolarBear]

Isn't urea the main component in urine? So why would anyone in this world make a solution of piss and boil it? It just doesn't make sense 😕

It's to get the pasta they are boiling to cook faster.

You piss in your pot of water and let your pasta cook under a powerful 100.12 C of heat instead of a weak 100 C, which will probably take forever.

Most people use salt, but urine works too.

 

[LetsGo2DSchool]

It's to get the pasta they are boiling to cook faster.

You piss in your pot of water and let your pasta cook under a powerful 100.12 C of heat instead of a weak 100 C, which will probably take forever.

Most people use salt, but urine works too.

Perhaps that's why there's an extra zing of taste in my pasta sometimes?

 

[AlbinoPolarBear]

Perhaps that's why there's an extra zing of taste in my pasta sometimes?

Perhaps you should bring up this issue to your mom or whoever cooked it.

But urine is pretty clean, you can drink it and not worry about getting sick.

Oh side note, back in the day, before the advent of chemical tests for sugars, doctors could figure out if you're a diabetic by tasting your urine. If it's sweet, you're a diabetic.

 

[predentlove]

mmm thanks so much !!! 🙂

A++++