Homework Help: chem

Posted by Angel Locsin on Friday, November 30, 2012 at 12:34am.

a.)How many moles of NaOH are required to prepare 2.00L od 0.380M solution? answer is 0.760 mole of NaOH (mole/l * 2.00L)
b.)What will be the molarity of a solution if 3.50 g of KOH are dissolved in water to make 150.0 mL of solution? answer is 0.52 M KOH (gKOH/molar mass KOH=mole KOH; M=mol KOH/L)
c.)What volume of (mL) of 0.400M solution can be prepared by dissolving 5.00g of KOH in water? answer is 300mL (gKOH/molar mass=mole KOH;mole KOH * Molarity of the solution 0.400M=L of solution *ml)
d.) Calculate the weight of HCl in 35.0mL of comcentrated HCl (12.00M) solution. my asnswer is 15 g HCl ( mL to L; L * M=mol; mole* molar mass= g)
pls check my answers.

chem - DrBob222, Friday, November 30, 2012 at 12:47am
I believe a is right with b and c wrong.
For d you appear to have rounded the answer to 15g; however, you ha e three significant figures is 35.0 and 4 s.f. in 12.00M, so don't throw a good digit away. You should have 3 s.f. in your answer.
b. mols KOH = 3.5/56.1 = ?mols
M = ?mols/0.150 = ? about 0.4M

c. mols KOH = 5.00/56.1 = about 0.89
M = mols/L or L = mols/M = 0.089/0.400M = about 0.22L
My answers are close; you should redo them for a more accurate answer. Also I've not kept up with the s.f. in my answers since they are estimates.

Answer this Question

Related Questions

chemistry 101 - If 15g of NaOh is dissolved in 285 g of water, calculate the ...
CHemistry - im not sure how u solve these types of problems... How many moles of...
Chemistry - I've been working on this problem for hours and cant figure it ...
CHEMISTRY - Not for homework, just practice problems I'm having trouble with...
chemistry - how much NaOH would be needed to dissolve in H2Oto prepare 2.00L of ...
Chemistry - I dissolved 4g of solid NaOH in 200mL of water. I converted grams of...
Chemistry - Use the dilution relationship (Mi x Vi = Mf x Vf) to calculate the ...
Chemistry-Is this correct? - The concentration of NaOH is normally in the range ...
Chemistry - What is the molarity of the resulting saline solution when you mix 1...
Chem - How would you prepare 150ml of .5M NaOH starting with a 6M solution of ...

For Further Reading

First Name:
School Subject:
Answer: