[browneyedbella]

1. How many grams of solute are present in 175 mL of 0.67 M glucose (C₆H₁₂O₆)?

0.67M/L * 0.175L * 180g/mol = 21.11g

2. How many grams of MgBr₂ should be dissolved in 275 mL of solution to produce a 0.32 M solution?

0.32M/L * 0.275L * 180g/mol = 15.84g

3. What volume of 12.4 M HCl would you need to make 500.0 mL of 3.50 M HCl?

(12.4M) * V = (0.500L)(3.50M)
V = .141 L = 14.1 mL

4. How many mL of 0.24 M KCl solution contains 0.56 g of KCl?

0.24 M * 0.56 g * 1 mol/74g = .0018 mL

5. a. Write a balanced net ionic equation for the reaction between lead (II) nitrate and cobalt (III) sulfate.

Pb²⁺ + SO₄^2-  PbSO₄

b. What volume of 0.250 lead (II) nitrate is required to react completely with 23.0 mL of 0.0356 M cobalt (III) sulfate?

0.023L * 0.0356M/L * (1 mol/1 mol) * 1L/0.250M = 3.3 x 10^-3L

6. 2.488g of an impure sample of Na3PO4 are dissolved in water and all of the PO₄^3- ions are precipitated to give 1.796g of Ca₃(PO₄)₂. What is the percentage of Na₃PO₄ in the original sample?

*** This is the only one I'm unsure of as my professor has yet to cover it. If you could help me on this one I'd appreciate it.

Also, if you catch any error with any of the above, please let me know!

Thanks in advance!!

[Astrokel]

4. How many mL of 0.24 M KCl solution contains 0.56 g of KCl?

0.24 M * 0.56 g * 1 mol/74g = .0018 mL

check again?

5. a. Write a balanced net ionic equation for the reaction between lead (II) nitrate and cobalt (III) sulfate.

put the symbol
Pb2+(aq) + SO42-(aq)     PbSO4(s)

b. What volume of 0.250 lead (II) nitrate is required to react completely with 23.0 mL of 0.0356 M cobalt (III) sulfate?

0.023L * 0.0356M/L * (1 mol/1 mol) * 1L/0.250M = 3.3 x 10-3L

Can you write a balanced equation? The stoichiometric coefficient might not be 1:1

6. 2.488g of an impure sample of Na3PO4 are dissolved in water and all of the PO43- ions are precipitated to give 1.796g of Ca3(PO4)2. What is the percentage of Na3PO4 in the original sample?

1. How many moles of PO₄^3- in Ca₃(PO₄)₂?
2. What is the moles of PO₄^3- in Na₃PO₄, is the same as 1. ye?
3. What is the moles of Na₃PO₄
4. What is the mass of Na₃PO₄
5. What is the % purity


you have done pretty good for other questions 

[browneyedbella]

I'm not sure by what you mean with #4....is it completely wrong or is my answer wrong?

Thank you for help with #5a.

As for #5b. I'm pretty bad at chemistry. lol. So you'll have to bear with me. Is the ratio 7:1? (.250/.0356 ??)


For #6...I'm really pretty lost. The mass of Na₃PO₄ is 164g. And the mass of Ca₃(PO₄)₂ is 310g. But that's all I know.

[Astrokel]

I'm not sure by what you mean with #4....is it completely wrong or is my answer wrong?

your math is wrong. Volume = Mole/molarity, but you multiply instead of divide.

As for #5b. I'm pretty bad at chemistry. lol. So you'll have to bear with me. Is the ratio 7:1? (.250/.0356 ??)

Pb(NO₃)₂ + Co₂(SO₄)₃  PbSO₄ + Co(NO₃)₃

balance it and you will see the ratio.

For #6...I'm really pretty lost. The mass of Na3PO4 is 164g. And the mass of Ca3(PO4)2 is 310g. But that's all I know.

huh, why 310g??? The question put 1.796g, no?

you know, moles of PO₄^2- in Ca₃(PO₄)₂ = moles of PO₄^2- in Na₃PO₄, ye? (law of conservation of mass)

So what is the moles of Na₃PO₄, and thus the mass? therefore you should be able to calculate the % of mass of Na₃PO₄ in the original sample.