1 12 What Is Concentration Part Ii

Launch: 1/12   Grab your binder and immediately take a seat!

  Place launch paper and HW (practice questions) on your desk.

  Yesterday’s Exit Slip Data:

  Today’s Objective: I can calculate the concentration of a solution in terms of molarity.

N/A

Launch: 1/12   Grab your binder and immediately take a seat!

  Place launch paper and HW (practice questions) on your desk.

  Yesterday’s Exit Slip Data:

  Today’s Objective: I can calculate the concentration of a solution in terms of molarity.

N/A

Launch: 1/12   Grab your binder and immediately take a seat!

  Place launch paper and HW (practice questions) on your desk.

  Yesterday’s Exit Slip Data:

  Today’s Objective: I can calculate the concentration of a solution in terms of molarity.

N/A

Launch: 1/12   Grab your binder and immediately take a seat!

  Place launch paper and HW (practice questions) on your desk.

  Yesterday’s Exit Slip Data:

  Today’s Objective: I can calculate the concentration of a solution in terms of molarity.

N/A

Launch 1/12 1.  In 1-2 sentences, explain what you did in lab on

Friday.

•  What variable did you change?

•  What were the results of your experiment?

Launch 1/11 2.  5 grams of sugar would dissolve the fastest in

a.  cold water. b.  warm water.

c.  hot water. d.  none of the above.

Launch 1/11 4.  Which of the following would dissolve the fastest in

water? a.  powdered sugar (most surface area) b.  granulated sugar (moderate amount of surface area)

c.  broken sugar cubes (moderate amount of surface area)

d.  sugar cubes (least amount of surface area)

Announcements   Late homework policy

  Late homework in now due the day after you return

  Quiz on Friday!

January Calendar

What is concentration? – Part II

Mr. Heffner 1/11/10

Review: What is concentration?   Concentration is…

  the amount of solute dissolved a in solution.

  Concentration is measured in…   grams per liter (g/L)

What is concentration?   Concentration is also measured in…

  Molarity = moles per liter (mol/L) = M   the # of moles of solute in one liter of solvent

  A mole is…   a unit of measurement (6.02 X 1023 atoms)

# of moles

volume

Examples 1.  If 2 moles of NaCl are dissolved in 1L of H2O, what is the

molarity of the solution in mol/L?

2 mol 1 L = 2 mol/L

In every 1L of solution, there are 2 moles of NaCl

= 2 M

“two molar”

Examples 2.  If 3 moles of NaCl are dissolved in 6L of H2O, what is the

molarity of the solution in mol/L?

3 mol 6 L =.5 mol/L

In every 1L of solution, there are .5 moles of NaCl

= .5 M

“point-five molar”

Examples 3.  How many moles of NaOH are needed to prepare 2.0 L of

a 2 M solution?

2 mol 1 L = 4 mol 2 L x 2 X 2 mol

1 =

2 M = 2 mol/L

Examples 3.  How many moles of HNO3 are needed to prepare 4 liters

of a 6 M solution?

6 mol 1 L = 24 mol 4 L x 4 X 6 mol

1 =

6 M = 6 mol/L

Whiteboards   Work in pairs

  Trade-off marker every question

  Partner without the marker should be checking work at each step!

  You have 60 seconds to solve the question   Show all of your work!   Don’t forget units!

  Lift board only when prompted

If 3 moles of Na2CO3 is dissolved in 1L of H2O,

what is the molarity of the solution in mol/L?

What is the molarity of the solution if 3 moles of KBr is dissolved in 6 liters of H2O?

How many moles of HCl are needed to make 10 liters of

a 4 M solution?

How many moles of KOH are needed to make .5 liters of

a 2 M solution?

Practice Questions   Practice question worksheet

Exit Slip 1.  Concentration is

a.  how well a solute dissolves in a given amount of solvent. b.  when two substances are not evenly mixed throughout.

c.  a measure of the amount of solute dissolved in a solution.

d.  reported in units of cm/L.

Exit Slip 2.  Concentration is calculated by

a.  dividing the mass of the solute by the volume of the solvent.

b.  summing the masses of all the parts in a solution. c.  multiplying the masses of the solute and solvent. d.  multiplying the volume of the solute by the mass of the

solvent.

Exit Slip 3.  If 60g of NaCl is dissolved in 20L of H2O, what is

the concentration of the solution in g/L? a.  2g/L b.  3g/L c.  6g/L

d.  120g/L

Exit Slip 4.  How many grams of salt are there in a .5L solution

of sugar water that has a concentration of 10g/L? a.  2g b.  5g c.  20g

d.  50g

Exit Slip 5.  If the solubility of C6H12O6 (sugar) is 40g/100L,

what mass of sugar can be dissolved in 50L of water? a.  .4g

b.  .4g/L c.  20g

d.  400g/L

Homework   Finish practice questions