GENERAL CHEMISTRY 1140

SOLUTION CONCENTRATION - MOLARITY

PREPARATION

DILUTION

 

MEASURING REAGENTS

MOST SOLIDS CAN BE WEIGHED ACCURATELY

BUT.....
HCl IS A GAS!

NaOH CAN'T PURCHASE 100% PURE

MANY REACTIONS HAVE TO BE RUN BY ADDING ONE SOLUTION TO ANOTHER

    AgNO3(s) + NaCl(s) ---> No Reaction
    AgNO3(aq) + NaCl(aq) ---> AgCl(s) + NaNO3(aq)

MEASURE VOLUME OF A SOLUTION USING GRADUATED CYLINDERS, MOHR PIPETS, VOLUMETRIC PIPETS, VOLUMETRIC FLASKS.

IF WE USE A SOLUTION

WE NEED TO KNOW

    HOW MUCH OF THE REACTANT IS IN THE SOLUTION?

    WE NEED A CONCENTRATION OF THE SOLUTION!

 

MOLARITY = M

    A ONE MOLAR SOLUTION HAS ONE MOLE OF SOLUTE DISSOLVED IN ONE LITER OF SOLUTION

 

1 M = 1 mol/1 liter = 1 mol/L

 

3.07 M = 3.07 mol/L

 

 

ASSUME I HAVE ONE LITER OF A ONE MOLAR SOLUTION OF NaCl

ASSUME I POUR 500 mL OF THE SOLUTION INTO A 500mL CONTAINER

    WHAT IS THE CONCENTRATION OF THE SOLUTION IN THE 500 mL CONTAINER?

 

IF I HAVE 100 mL OF A 1 M HCl SOLUTION, HOW MANY MOLES OF HCl DO I HAVE?

 

IF I HAVE 75 mL OF A 2.0 M NaOH SOLUTION, HOW MANY MOLES OF NaOH DO I HAVE?

 

WHAT IS THE MOLARITY OF A 500.0 mL SOLUTION PREPARED FROM 18.2 g NaOH?

 

MOLARITY = MOLES/LITER
    FIND MOLES AND FIND LITERS!!!

 

 

YOU NEED 100.0 mL OF A 0.478 M SODIUM HYDROXIDE SOLUTION. HOW MUCH SOLID SODIUM HYDROXIDE MUST YOU WEIGH OUT?

 

 

PROBLEMS:
YOU CANNOT OBTAIN PURE SODIUM HYDROXIDE
SOLID SODIUM HYDROXIDE PICKS UP MOISTURE FROM THE AIR

    PREPARE A CONCENTRATED SOLUTION AND DILUTE IT!

 

HOW MUCH 6.00 M NaOH IS REQUIRED TO PREPARE 100.0 mL OF 0.478 M SODIUM HYDROXIDE SOLUTION?
 

 

NOTE: A 0.200 M SOLUTION OF SODIUM SULFATE WOULD BE:

0.400 M IN SODIUM ION

0.200 M IN SULFATE ION

 

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