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USF - Chem 2045 - Class Notes - Week 4

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4.4 Solution Concentration and Solution StoichiometryIf you want to learn more check out What is the definition of timed drew?

Solution - homogeneous mixture → looks the same, can’t tell by looking at it that it’s a solution

Solvent - what does the dissolving → moreWe also discuss several other topics like What is the first American Avant-Garde group?

Solute - what is dissolved → less

Aqueous solution → solution with water

**TIP** “solvent” has more letters than “solute”, so there is always more of the solventDon't forget about the age old question of What are the benefits of working in a highly competitive rapidly changing retail environment?

- Solution Concentration = Molarity

Molarity(M) =

Example: What is the molarity of a solution containing 25 grams of NaCL in 2.75 liters of water?If you want to learn more check out michael lynch uga

Given: 25 g NaCL find: molarity of the solution

2.75 L waterWe also discuss several other topics like What are the factors of fashion as a form of communication?

Use molarity formula

Molarity(M) =

Step 1:Convert grams to molesIf you want to learn more check out How is force related to acceleration?

x= 0.428 mol NaCL

Molar mass

Step 2:Plug valves into formula and solve

M =

M = 0.156 mol / L

- Molarity in Calculations

Example: How many liters of 0.125 M NaCL solution contain 0.255 mol NaOH?

Given:

0.1256 M NaOH Find: volume (L) of solution

0.255 mol NaOH

This is what we have

M = this is what we are looking for

Step 1:Plug in values

0.125 M NaOH =

Step 2:Solve for the unknown

Volume (L) =

Volume = 1.8 L of solution

**TIP**

Always write and carry through the units and the type of chemical you are using in calculations. This will prevent simple mistakes and provide a quick way to check your work. If your units don’t match, you did something wrong!

- Solution Dilution

M1V1 = M2V2

M1 = molarity of initial solution M2 = molarity of final solution

V1 = volume of initial solution V2 = volume of final solution

**HINT**

This formula is used for more than dilutions, it is also used for acid - base titrations - Memorize this formula!

**TIP**

Volume does not have to be in liters as long as the units match!

Example: What volume of water is needed to dilute 200 mL of 5 M HCL to 0.1 M HCL?

Given: 200 mL HCL (initial) find: V2

5 M HCL (initial)

0.1 M HCL (final)

Step 1: Plug in knowns to the M1V1 = M2V2 formula

(5 M HCL)(200 mL HCL) = (0.1 M HCL)(V2)

Step 2: Solve for the unknown

= V2

V2 = 10,000 mL → or 10 L

- Solution Stoichiometry

Example: What volume, in mL, of a 0.15 M HNO3 solution will react completely with 3.75 mL of 0.108 M Na2CO3 solution according to the following balanced chemical equation

Na2CO3(aq) + 2HNO3(aq) → 2NaNO3(aq) + CO2(aq) + H2O(e)

Given:

0.15 M HNO3 find: volume of HNO3

3.75 mL Na2CO3

0.108 M Na2CO3

Step 1: Find the number of moles of Na2CO3 using molarity equation

M =