## Normality and Molarity p 218Molarity is moles per liter of solution.
liter
We use Normality when discussing solutions especially acids and bases. HCl + Na(OH) ----> NaCl + HOH If I had 100 milliliters of a 1 M HCl acid, how many moles of H
Let's look at H H Each molecule of H If I had 100 mL of a 1 M H 1 liter of a 1 M Na(OH) would have 1 mole of (OH) If I mixed 1 L of 1 M Na(OH) with 1 L of 1 M H I have 2 times as much H When using acids and bases we use Normality (N) instead of Molarity (M). 1 M HCl = 1 N HCl H If I had 100 milliliters of a 1 M H
a 1 M H
1 M Ca(OH)
HCl has only 1 hydrogen
H a 1 M HCl is a 1 N HCl a 1 M H Examples
What is the normality of 3 M H
x = 6
What is the molarity of 6 N H 1 M H
x = 2
Problems Determine the normality of 1.5 M HNO 0.55 M H 0.0023 M Ca(OH) Determine the molarity of 0.9 N NaOH 1.3 N HCl 0.06 N H 0.3 N H 12 N Ca(OH)
If I had 50 H If I had 50 H+, how many (OH)- would I need to neutralize it?
We frequently use the term EQUIVALENTS or MILLIQUIVALENTS You can think in terms of moles of H
moles = Molarity x L Equivalents = Normality x L
Milliequivalents = Normality x Milliliters If I had 50 mL of a 2 N H(SO) How many milliequivalents of hydroxyl would I need to neutralize it?
1. How many milliliters of a 0.02 N NaOH would be needed to neuralize 35milliliters of a 0.15 N HCl?
2. What is the normality of a solution of HCl, if 50 mL of the HCl were neutralized by 30 mL of a 0.15 N NaOH?
Dilutions Suppose I had 12 N HCl and wanted to make up 200 mL of 0.1 N solution. How many milliliters of the concentrated solution would I need to make up 200 mL of the dilute solution? How many milliequivalents of H+ would I need in 200 mL of 0.1 N HCl
So how many milliequivalents would I need to take out of the concentrated HCl solution? How many milliliters would have that number of milliequivalents?
(N) (ml) = (N) (mL) How many milliliters of a 6 N NaOH would I need to make up 100 mL of a 1 N NaOH?
Problems 1. How many milliliters of 2N HCl would be needed to make 100 mL of 0.1 N HCl?
2. What is the Normality of a NaOH solution if it took 25 mL of a 0.1 N HCl to neutralize 10 mL of the NaOH?
3. How many milliequivalents of H
4. What is the normality of a HCl solution if 10 mL of 12 N HCl were brought up to a 1 L volume?
5. How many milliequivalents of NaOH are needed to neutralize 50 mL of a 0.2 N HCl solution?
6. How many grams of NaOH are needed to make 100 mL of 0.5 N NaOH? (hint: N = M for NaOH M = grams/ MW)
7. How many grams of H
PROBLEMS 1. Calculate the mass percent of solute in 25.0 g of KNO
2. Calculate the mass, in grams, of solute needed to prepare 24.0 grams of a
13.5% by mass sucrose (C
3. Calculate the volume percent of solute in 75.0 g ethylene glycol in enough water to give 200 mL of solution.
4. What is the percent by volume of isopropyl alcohol in an aqueous solution made by diluting 20 mL of pure isopropyl alcohol to a volume of 125 mL.
5. Calculate the mass/volume percent of magnesium chloride of 1.0 g MgCl
6. How many grams of NaCl are present in 15 mL of a 2.0% solution?
7. How many grams of solute are present in 375 mL of 7.5 M CaCl
8. Given a 2.0 M solution of NaCl. How many milliliters of the solution would be needed to get 1.0 gram of NaCl?
9. 5.85 grams of NaCl were dissolved in water. The final volume was 100 mL. A) What is the molarity? B) What is % w/v?
10. Concentrated HCl is 12 N. How many milliliters of the concentrated acid wuld be needed for 100mL of a 0.15 N solution? 11. How many grams of sulfuric acid H
12. How many meq of H
13. What is the normality of a HCl solution which contains 50grams of HCl per liter? 14. What is the normality of a 4 M H
15. How many mL of a 0.3 N NaOH solution would be required toneutralize 50 mL
of a 0.4 N solution of H
16. How many milliequivalents are present in 15 mL of a 2 N solution?
17. How many milliquivalents of acid are requird to neutralize 20 milliequivalents of base?
18. How many mL of a 0.15 N HCl would be required to neutralize 40 mL of a 0.20 N NaOH?
19. It took 35 mL of an acid of unknown normality to neutralize 25 mL of 0.12 N NaOH. What is the normality?
20. How many milliliters of a a 0.20 M H
21. How many mL of a 12 N HCl solution would be needed to make 100 mL of a 0.15 N solution?
22. 15 mL of a 10 N NaOH solution was diluted to a volume of 1 liter. What is the normality of the new solution.?
23. Given 3.92 grams of H a) What is the Percent solution? Questions Chapter 8 8.45; 8.26; 8.47; 8.49; 8.51
10 10
Drill Write the log of We can do logs of numbers other than powers of 10. 10 10 log of 10 = 1 so the logs of numbers between 1 and 10 are decimals.
Where do we get them?
log of 4 = .6621 Find the log of
(a) 30
Find the log of 0.0083.
Drill Find the log of
pH refers to the concentration of [H
pH is the negative log of [H pOH refers to the negative log of [OH]
If we know the pH we can find out the pOH.
The pH is 4. What is the pOH? pH + pOH = 14 The pOH is 3. What is the pH?
pH 7 is neutral
The molarity of a solution of HCl is .015 M. What is its pH? (Find the log of 0.015). What is the pH corresponding to a hydrogen ion concentration
of 5 x 10
The pOH is 8. (a) What is the pH?
(b) What is the [H pH = 6 -6 is the neg. log. 1 x 10
(1) pOH = 4 (6) 1 x 10
To go from the pH to the concentration, we must reverse the steps. To find the pH from the concentration of 2.3 x 10 2.30 exp 4 +/- log +/- Ans 3.64 To go from the pH 3.64 to concentration, the steps are 3.64 +/- inv or 2nd log Ans 2.30 x 10 On some calculators the steps are
What is the H pH 3
pOH 5 Questions Chapter 8: 8.28; 8.29; 8.30; 8.32 |

Wednesday, March 21, 2007 01:28:01 PM |