Chemistry - Water and Properties of Solutions

Question 1

What are the 5 properties of water and be able to describe them

Answer 1

• Highly polar: oxygen is slightly negative and the hydrogens are slightly positive
• High specific heat: takes lot of E to increase temp of water
• Hydrogen bonding: H bonds form between water bc of polarity
• Cohesive: molecules stick to each other = surface tension and reistant to rupture
• Adhesive: sticks to other polar molecules when attracted by oppositve charge

Question 2

_________ is the universal solvent

Answer 2

water

Question 3

What types of things will water NOT be able to dissolve?

Answer 3

Nonpolar molecules (fats, substances that have hydrocarbons)

WATER CAN DISSOLVE POLAR SUBSTANCES (substances that have O are usually polar)

Question 4

Substances that have ________ are usually polar

Answer 4

Oxygen

Question 5

What is the formula for molarity (M)?

Answer 5

mol/L (of solution)

Question 6

Molarity is temperature ___________, beecause increasing the temperature can cause the _______ to change

Answer 6

dependent
volume

Question 7

What is the equation for molality (m)?

Answer 7

mol/kg (of solvent)

Question 8

What does a dilution factor tell us?

Answer 8

how much of the original stock solution remains in a solution

Question 9

What does it mean when a dilution appears like this 1:10

Answer 9

1mL of stock is added to 9ml of water

Question 10

What is the equation for dilution factor?

Answer 10

DF = total volume/stock volume

Question 11

eq

What is the dilution factor if you take 50mL of bacterial stock solution and mix it with 200mL of growth media?

Answer 11

(200+50)/50 = 250/50 = 5

Question 12

A research student performs a 1:10 series dilution of bacterial stock solution. She determines that tube #4 contains a total of 1,000 bacterial cells. How many total cells are in tube #1?

Answer 12

1,000,000

If she has 1,000 bacterial cells in tube 4, we must divide by 10, until we reach tube #1. We divide by 10 because the DF is 10. If you do this, then we eventually get 1,000,000 bacterial cells.

Question 13

If 225 ml of water is added to 25 ml of 5.0 M NaCl, what is the concentration of the dilute solution?

Answer 13

0.5 M

1) Find dilution factor
2) DF = 250/25 = 10
3) NaCl solution is being diluted by a factor of 10, so we take the concentration (5.0M) and divide by 10
4) 5.0M/10 = 0.5M

Question 14

Which of the following statements about the result of diluting 1.00 L of 9 M HCl to 2.00 L is true?

• The diluted solution is 18 M.
• The concentration remains the same
• The dilution contains 4.5 moles of HCl
• The diluted solution contains 9 moles of HCl

Answer 14

• The diluted solution contains 9 moles of HCl