Anyone wanna help an old member with some good old chem problems?

[Kay]

[redacted]

[Korean Ninja]

i hope u like physics

[Im a Jackass]

google is your best friend or just copy it from one of the other kids in your class

[Wicked Pissah]

Something suspicious: Chemistry help please? - Yahoo! Answers

FOUND YOU! Yahoo Answers is sadly probably one of your better options.

[Zopy]

1.

Molality = moles Solute/kg solvent

Our solvent is water and we have .18 kg of that. We know our molality is 0.36, so we can set up the equation:

0.36= x/.18     where x is how many moles we have. After solving, you get x= 0.0648 moles.

Since we have 15.6 of the substance, and that is 0.0648 moles, you can simply divide both numbers by 0.0648 to get the molar mass. In this case it's 240.7 g/mol

 

2.

We know we need a .5587 molar solution. So .5587 moles for 1 Liter of solution. .5587 moles of NH3 is 9.51 grams. But that's for 1 liter and we only need .257 liters. Then you can set up a simple proportion.

9.51g/1 L = x g/0.257 L

x is about 2.44 grams of NH3

 

3.

This is simple Molality is the moles of solute divided by the kg solvent. From the information we know we have .0298 moles of the salt for every 2.2 kg of water. 

Simply divide it out and you'll find your Molality is 0.1354 mol/ 1kg Water

 

4.

This is a bit longer.

30% of our solution is Z. 70% is water. Water has a density of 1.00 g/mL.

We have to make an assumption on this one about how much of this solution we have. It can be whatever, you'll get the same answer. I'm just going to say we have 1 liter.

Since we have 1 liter of the solution, and it has a density of 1.11 g/mL, we know we have 1,110 grams of the solution. 70% of this solution is water, which means 777 grams of it is water, and 333 grams is solute Z.

Now we can use math to set up the following equation to determine how many moles we have:

333 g/ 281.6 g     It turns out we have 1.1825 moles of Z for every one liter of solution. Giving us our answer :

Molarity(Z)= 1.1825 mol/1 L Sol

 

I didn't do five for you because I figure you can get it on your own if you try hard enough, which is what homework is all about. I'm 99% sure that what I did is correct.

[Jewpiter]

In most cases suicide is never the answer, for your assignment, however, it is an exception.

[Im a Jackass]

1.

Molality = moles Solute/kg solvent

Our solvent is water and we have .18 kg of that. We know our molality is 0.36, so we can set up the equation:

0.36= x/.18     where x is how many moles we have. After solving, you get x= 0.0648 moles.

Since we have 15.6 of the substance, and that is 0.0648 moles, you can simply divide both numbers by 0.0648 to get the molar mass. In this case it's 240.7 g/mol

 

2.

We know we need a .5587 molar solution. So .5587 moles for 1 Liter of solution. .5587 moles of NH3 is 9.51 grams. But that's for 1 liter and we only need .257 liters. Then you can set up a simple proportion.

9.51g/1 L = x g/0.257 L

x is about 2.44 grams of NH3

 

3.

This is simple Molality is the moles of solute divided by the kg solvent. From the information we know we have .0298 moles of the salt for every 2.2 kg of water. 

Simply divide it out and you'll find your Molality is 0.1354 mol/ 1kg Water

 

4.

This is a bit longer.

30% of our solution is Z. 70% is water. Water has a density of 1.00 g/mL.

We have to make an assumption on this one about how much of this solution we have. It can be whatever, you'll get the same answer. I'm just going to say we have 1 liter.

Since we have 1 liter of the solution, and it has a density of 1.11 g/mL, we know we have 1,110 grams of the solution. 70% of this solution is water, which means 777 grams of it is water, and 333 grams is solute Z.

Now we can use math to set up the following equation to determine how many moles we have:

333 g/ 281.6 g     It turns out we have 1.1825 moles of Z for every one liter of solution. Giving us our answer :

Molarity(Z)= 1.1825 mol/1 L Sol

 

I didn't do five for you because I figure you can get it on your own if you try hard enough, which is what homework is all about. I'm 99% sure that what I did is correct.

 

why would you do it for him he is going to end like Korean Ninja and not know any thing about the topic

[Determined2Win]

1. What is the molecular weight of a substance

if 15.6 grams of it dissolved in 180 grams of

water form a 0.36 molal solution?

Answer in units of g/mol.

 

2. How much ammonia would have to be dissolved in water to form 257 mL of solution

which is 0.5587 molar?

Answer in units of g

 

3. 0.298 moles of FeCl3 (a salt) is dissolved in 2.2

liters of ordinary water (density 1.0 g/mL).

What is the molality of this solution?

Answer in units of mol/kg

 

4. Consider an aqueous solution that contains

30 % (by mass) of a hypothetical solute Z.

The formula weight of the solute Z is 281.6.

The density of the solution is observed to be

1.11 g/mL. What is the molarity of Z in this

solution?

Answer in units of molar

 

5. When 0.083 mol of aluminum sulfate are dissolved in enough water to make 617 milliliters

of solution, what is the molar concentration

of aluminum ions?

Answer in units of M.

 

Any help will be greatly appreciated. God knows, we all abhor chemistry! BTW, hi everyone!

 

Unrelated, but why is your brother favoriting anti-Bullying videos on YouTube? Is he being bullied? I'll fuck up any mother fucker who fucks with my jiggs.

 

Also, don't ask me how I know his YouTube.

[Zopy]

why would you do it for him he is going to end like Korean Ninja and not know any thing about the topic

Because I'm a doormat ):

[Kay]

[redacted]