Normality Analytical Chemistry Part 2 Summary PDF

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 Normality (N) is the number of equivalent weight per 1 liter of solution 𝐀𝐀𝐀𝐀𝐀 𝐀𝐀 𝐀𝐀𝐀𝐀𝐀𝐀 𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀 = 𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀 𝐀𝐀𝐀𝐀ℎ𝐀 𝐀 𝐀𝐀𝐀𝐀𝐀 𝐀𝐀 𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀 Where; 𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀𝐀 𝐀𝐀𝐀𝐀ℎ𝐀 77 grams of NaCl is dissolved in 250 mL of water. What is the molar concentration of the solution?  MW of Na = 23, MW of Cl = 35Answe...

Description

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Sometimes confused with Molarity. Molarity is expressed as the number of moles per liter of solution, while molality is expressed as Moles/kilogram of solvent

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NORMALITY Normality (N) is the number of equivalent weight per 1 liter of solution

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Answer: 5.34 M 

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 Valence of Acids – according to the number of hydrogen ions Valence of Bases- according to number of hydroxyl ions

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Weight/Volume (w/v) % solutions  ��� � ℎ�/������% =

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Most common type of solution prepared in the clinical lab Volume/Volume % solutions 

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× 100

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%=

× 100

Weight/weight (w/w) % solutions ℎ�/����ℎ� % solution =  ��� � ����ℎ� �� ������

Compute first for the amount of Barium chloride Then subtract the amount of Barium chloride to the total volume to determine the amount of Sulfuric acid

Answer: 0.05 mL of Barium chloride and 9.95 mL of Sulfuric acid

PERCENT SOLUTIONS

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A 10 mL of 0.5% solution composed of Barium chloride and sulfuric acid is to be prepared. How many mL of Sulfuric acid is needed? 

� �������� = � ������� � ������� ��������� ��� ����� = �������

How many grams of HCl is needed to prepare a 100 mL of 0.1N HCl solution? (MW: 36 g/mol)

Answer: 0.36g HCl

RELATIONSHIP BETWEEN MOLARITY AND NORMALITY

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How many grams of CaCl2 is needed to prepare a 10 mL of 0.02M solution?  Ca (40 g/ mol) Cl (35g/mol)

Answer: 0.022 grams

Where;

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77.4 grams of NaCl is dissolved in 250 mL of water. What is the molar concentration of the solution?  MW of Na = 23, MW of Cl = 35

5. Calculate the amount of water you need to add to make a final concentration of 70% ethanol solution by using 100 mL of pure (100%) ethanol. C1V1=C2V2

Answer: 42.9 mL of water The final volume we need to make therefore is 142.9 mL. We know 100 mL of that is the 100% pure ethanol, so the volume of water must be 42.9 mL (142.9 – 100 = 42.9). So, adding 42.9 mL of water to 100 mL of 100% pure ethanol will achieve fi l i f 70% h l

knowing that there are always 1000 grams in one kilogram. Or we can convert lengths, say, from kilometers to miles.

DIMENSIONAL ANALYSIS (the study of)the relationship between the quantities of substances involved in a chemical reaction and the substances that are produced as a result of that chemical reaction

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5 x 5 = 52 cm x cm = cm2 �� ��

EXERCISE How many moles of water is present in 36 grams of the same substance?

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How many carbon atoms are present in 8.97 grams of ethane? How many moles of Na are in 5.63 grams Na2SO4? 

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2 moles of H2O 3.59 or 4.00 x 1023 atoms of C 0.08 moles of Na

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: Identify the known or given quantity and the units of the new quantity to be determined. Write an equation with the given quantity on the left and the units of the desired quantity on the right. Multiply the given quantity by one or more conversion factors in such a manner that the unwanted (original) units are canceled, leaving only the desired units Perform the mathematical operations indicated by the conversion factor setup.

SAMPLE PROBLEM

DIMENSIONAL ANALYSIS 

Dimensional analysis is a general problemsolving method in which the units associated with numbers are used as a guide in setting up calculations

A standard aspirin tablet contains 324 mg of aspirin. How many grams of aspirin are in a standard aspirin tablet? Step 1: 324 mg = ? G Step 2: Use of conversion factor 1 0.001 0.001or � 1 �� 0.001

324 mg x g

=?

1

Step 3: 0.001 ሺ 324 ሺ= 0.324 g 1

Or 1 g is = 1000 mg

Dimensional Analysis is a way chemists and other scientists convert units of measurement. We can convert any unit to another unit of the same dimension. •

This means we can convert some number of seconds into another unit of time, such as minutes, because we know that there are always 60 seconds in one minute. Or we can convert some amount of mass from grams to kilograms,

ATOMIC MASS 

The mass of atoms of elements expressed in atomic mass units (amu)

MOLECULAR WEIGHT 

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Sum of the atomic weights for the atoms in a molecule For the molecule ethane, C2H6, the molecular weight would be...