Solutions

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# Solutions - PowerPoint PPT Presentation

Solutions. Why does a raw egg swell or shrink when placed in different solutions?. Some Definitions. A solution is a HOMOGENEOUS mixture of 2 or more substances in a single phase. One constituent is usually regarded as the SOLVENT and the others as SOLUTES. Parts of a Solution.

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## Solutions

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Solutions

Why does a raw egg swell or shrink when placed in different solutions?

Some Definitions

A solution is a HOMOGENEOUSmixture of 2 or more substances in a single phase.

One constituent is usually regarded as the SOLVENTand the others as SOLUTES.

Parts of a Solution
• SOLUTE – the part of a solution that is being dissolved (usually the lesser amount)
• SOLVENT – the part of a solution that dissolves the solute (usually the greater amount)
• Solute + Solvent = Solution

moles solute

(

M

)

=

Molarity

liters of solution

Concentration of Solute

The amount of solute in a solution is given by its concentration.

Think of O.J!
• Do you like Concentrated Orange Juice?
• What does that mean?
• What if we could describe the amount of Orange Juice in a solution.
• That’s why we have Molarity!!!

To make a 1 M solution of Copper (II) Sulfate

Add 1 Mole of Copper Sulfate

Add Enough water so that the SOLUTION has a volume of 1 L

PROBLEM: Dissolve 5.00 g of NiCl2•6 H2O in enough water to make 250 mL of solution. Calculate the Molarity.

Step 1: Calculate moles of NiCl2•6H2O

Step 2: Calculate Molarity

[NiCl2•6 H2O] = 0.0841 M

USING MOLARITY

What mass of oxalic acid, H2C2O4, is

required to make 250. mL of a 0.0500 M

solution?

Step 1: Change mL to L.

250 mL * 1L/1000mL = 0.250 L

Step 2: Calculate.

Moles = (0.0500 mol/L) (0.250 L) = 0.0125 moles

Step 3: Convert moles to grams.

(0.0125 mol)(90.00 g/mol) = 1.13 g

moles = M•V

Learning Check

How many grams of NaOH are required to prepare 400. mL of 3.0 M NaOH solution?

1) 12 g

2) 48 g

3) 300 g

Solution

M = moles of solute Liters of solution

M * V = moles

3.0 mol/L * 0.400 L = 1.2 mol NaOH

1.2 mole NaOH x 40.0 g NaOH 1 mole NaOH

= 48 g NaOH

Preparing Solutions
• Weigh out a solid solute and dissolve in a given quantity of solvent.
Mixing Solutions

How would you make 500.mL of a 2.50M NaOH solution?

Step 1: Convert volume mL to L.

500.mL * 1L/1000mL = .500L

Step 2: Calculate number of moles NaOH needed.

moles = M * liters

moles = 2.50M * .500L = 1.25 moles NaOH

How can you “Dilute Solutions”
• MV=MV

How would you make 100 mL of a .1 M NaOH solution from a 1 M stock solution?

(.1L)(.1M/L) =1M X

1M

.01 L or 10 mL and add 90 mL of water