Posted by **Robert** on Monday, February 22, 2010 at 1:30pm.

Please help. I have no idea how to do these 4 homework problems.

1- How many milliliters of 0.140 M HCl are needed to completely neutralize 42.0mL of 0.106 M Ba(OH)2 solution?

2-How many milliliters of 0.123 M H2SO4 are needed to neutralize 0.250 g of NaOH ?

3-If 55.2 mL of BaCl2 solution is needed to precipitate all the sulfate ion in a 750 mg sample of Na2SO4 , what is the molarity of the solution?

4-If 42.7 mL of 0.218 M HCl solution is needed to neutralize a solution of Ca(OH)2 , how many grams of Ca(OH)2 must be in the solution?

- Chemistry please help! -
**DrBob222**, Monday, February 22, 2010 at 2:14pm
1- How many milliliters of 0.140 M HCl are needed to completely neutralize 42.0mL of 0.106 M Ba(OH)2 solution?

**
**

Step 1. Write a balanced equation.

2HCl + Ba(OH)2 ==> BaCl2 + 2H2O

Step 2. How many moles of the base do we have. moles = M x L = 0.106 M x 0.042 L = 0.00445.

Step 3. How many moles of HCl are needed? Use the coefficients in the balanced equation to do this. We have 0.00445 moles Ba(OH)2. It takes twice as much HCl as it does Ba(OH)2; therefore, we must have used 2 x 0.00445 moles HCl = 0.00890 mols HCl.

Step 4. Remember the definition of molarity. M = moles/L. For the HCl we have 0.00890 moles and the molarity is 0.140 M, so solve for L.

L = mols/M = 0.00890/0.140 = 0.0636 L or 63.6 mL.

All of the solution problems are worked the same way. If the problem throws in a solid instead of a solution, just remember that moles = grams/molar mass. After converting into moles, everything is worked the same way. Try it, you'll like it.

- Chemistry please help! -
**Dev**, Wednesday, March 30, 2016 at 8:17pm
On step 3 you divide by 2 not multiply.

## Answer This Question

## Related Questions

- Chemistry - How many milliliters of 0.135 M HCl are needed to completely ...
- chemistry - How many milliliters of 0.155 M HCl are needed to neutralize ...
- Chemistry - What is the concentration of an HCl solution if 23.1 mL of HCl are ...
- Chemistry - How many milliliters of a 0.20 M KOH are needed to completely ...
- Chemistry Help - How many milliliters of 0.534 M Ba(OH)2 solution are needed to ...
- Chemistry - 1)A buffer solution that is 0.10 M sodium acetate and 0.20 M acetic ...
- Chemistry - 1)A buffer solution that is 0.10 M sodium acetate and 0.20 M acetic ...
- chemistry - Determine how many milliliters of 0.102M NaOH solution is needed to ...
- chemistry - How many mL of 0.100M HCl are needed to neutralize 49.0mL of 0.104M ...
- chemistry - What is the concentration of an HCl solution if 23.1 mL of HCl are ...

More Related Questions