Practice for Final Exam

1. 9.35g of Al₂O₃ contains how many molecules?
2. 0.253 moles of BN has a mass of…
3. Calculate the number of moles of 8.46 x 10²⁴ atoms of F.
4. Calculate the number of moles of 4.35g of Cs₂CO₃.
5. 0.692moles of CsH contains how many molecules?
6. How many moles are in 14.49 g of CoSO₄.
7. What is the mass of 7.20 x 10²³ atoms of Ne?
8. 50.82 g of Cr₂O₃ has how many moles?
9. 2.84 moles of N₂H₄ has how many molecules?
10. 5.29 x 10²⁴ molecules of HCl has a mass of…
11. In a 30.0 g sample of Pb(NO₃)_2, Pb has a mass of 2.535 g, N a mass of 8.694 g, and O a mass of 18.768 g. What is the % composition?
12. In a 25.0 g sample of Hg₂Cl₂, Hg has a mass of 3.755 g and Cl has a mass of 21.245 g. What is the % composition.
13. In a 20.0 g sample of Ni(NO₃)₂, Ni has a mass of 3.066 g, Ni has a mass of 6.426 g, and O has a mass of 10.508 g. What is the % composition?
14. What is the % composition of the following:
• KMnO₄
• Sc₂O₃
• H₂SeO₄
• Cl₃HSi
• NaBrO
15. What volume of 0.075 M HCl is required to neutralize 100 mL of 0.01 M NaOH solution?
16. What is the concentration of NaOH if 45.2 mL of 1.5 M H₂SO₄ is needed to neutralize 20.0 mL of NaOH: H₂SO₄ + 2NaOH ➝ Na₂SO₄ + 2H₂O?
17. Find the [H₃O⁺] and pH of the following: 0.075 M HCl 
18. Find the [H₃O⁺] and pH of the following: 0.122 M H₂SO₄
19. Calculate the [H₃O⁺] and pOH of the following solution: pH = 9.5
20. Calculate the [H₃O⁺] and pOH of the following solution: [OH^-] = 3.9 x 10^-12
21. Find the [OH^-] of the following solutions: pOH = 1.5, pH = 4.6, & [H₃O⁺] = 2.5 x 10^-9
22. In the following chemical reactions, identify the acid, base, conjugate acid, and conjugate base.
• HC₂H₃O₂ + H₂O ⇌ H₃O⁺ + C₂H₃O₂^-
• NH₃ + H₂O ⇌ NH₄⁺ + OH^-
• HNO₃ + H₂O ⇌ NO₃^- + H₃O⁺
23. Find the [H₃O⁺] and pH of the following:
• 0.025 M HNO₃
• 3.4 x 10^-4 M H₂SO₄
24. Calculate the [H₃O⁺] and pOH of the following solutions:
• pH = 3.2
• pH = 5.0
• [OH^-] = 8.2 x 10^-9
• pH = 12.4
25. Find the [OH^-] of the following solutions:
• [H₃O⁺] = 3.9 x 10^-6 M
• [H₃O⁺] = 0.0014 M
• pH = 4.2
26. If 35.2 mL of 12M HCl is used to titrate 50.0 mL of KOH, what is the concentration of the KOH?
27. What is the volume of 2.5 M NaOH needed to titrate 25.0 mL of 1.0 M HCl?
28. Given the following equation, find the concentration of NaOH when 24.09 mL of 1.605 M H₂SO₄ is needed to titrate 50.0 mL of NaOH.      H₂SO₄ + 2NaOH ➝ Na₂SO₄ + 2H₂O
29. What is the salt that is formed during the following neutralization reactions?
• Mg(OH)₂ + HCl ➝ ? + H₂O
• H₂SO₄ + 2NH₄O ➝ ? + 2H₂O
• Ni(OH)₂ + 2HClO₄ ➝ ? + 2H₂O
• Mg(OH)₂ + H₂SO₄ ➝ ? + 2H₂O
30. Balance the following redox reactions:
• Na + H₂O → NaOH + H₂
• HCl + HNO₃ → HOCl + NO + H₂O (*Cl on the product side has an oxidation number of +1)
• SnCl₄ + Fe → SnCl₂ + FeCl₃
• CO + I₂O₅ → I₂ + CO₂
• MnO₄^- + Fe²⁺ + H⁺ → Fe³⁺ + Mn²⁺ + H₂O
• Cu⁺ + Fe → Fe³⁺ + Cu

Proteins and Nucleic Acids

Proteins

• Most important substance in the bodies of living things.
• Building blocks for muscle, hair, blood cells, skin, slk, enzymes, insulin, etc.

Amino Acids

• Building blocks of proteins.
• Contain an amine (NH2) group and carboxyl (COOH) group.
• Various side chains (R groups) attach to the carbon adjacent to the N.
• Results in 20 different common amino acids.
• Our bodies can synthesize 12 out of 20.
• The other 8 must come from diet
• Known as essential amino acids

List of Amino Acids

Polypeptide Chains

• Amino acids joined together with peptide bonds.
• Dipeptides: two amino acids joined together
• Aspartame (artificial sweetener)
• Polypeptides: polymers of many amino acids

Polypeptide chain or protein

Proteins

• Polymer of one or more polypeptide chains.
• Some contain several hundred amino acids others several thousand.
• Various structures

Nucleic Acids

DNA Structure

• When cells reproduce, they pass genetic information to one another in long-chain molecules called chromosomes.
• Human body contains 46 chromosomes in the nuclei.
• Segments of chromosomes, called genes, carry the coded information to that directs the production of specific polypeptide chains.
• Nucleotides are the building blocks of nucleic acid.
• Three units:
• 5 carbon sugar (ribose or dioxyribose)
• phosphate group
• ring-shaped nitrogen containing base
• There are five possible nitrogen-congaing bases attached to the sugar:
• Adenine (A)
• Cytosine (C)
• Guanine (G)
• Thymine (T)
• Uracil (U)
• DNA has A, C, G, T
• RNA has A, C, G, U
• DNA is two strains coiled around each other in a double helix
• When cells divide, a DNA strand reproduces by first unraveling with the help of enzymes. 
• Each of the two resulting strands serves as a template, or pattern, for a new complementary chain.
• Complementary bases on the newly forming strand match the now-exposed bases of the old strand.
• When the process of replication is completed, two identical double-stranded DNA molecules result. 

DNA Replication

• One strand goes to each half of the dividing cell.
• DNA and RNA molecules instruct cells on how to make proteins.
• DNA is used as a template to make RNA.
• RNA is made up of nucleotides.
• Trinucleotide groups (3 nucleotides) code for various amino acids.
• As the amino acids join together, they form proteins. 
• The proteins are the chemical manifestation of our physical characteristics. 

This is an example of protein synthesis from RNA

Differences between DNA and RNA

• DNA
• the sugar is deoxyribose
• contains thymine
• double strand
• RNA
• the sugar is ribose
• contains uracil
• single strand

Carbohydrates

• Most abundant biological compounds.
• Sugars and starches make up a large part of the human diet.
• Each year photosynthetic processes in plants convert water and carbon dioxide into one hundred billion tons of carbohydrates.
• Exoskeletons of insects are made of carbohydrates.

• All carbohydrates have several of the –OH (hydroxy) groups common to alcohols.
• They also have the C=O (carbonyl) group of aldehydes and ketones.
• They are known as one or more polyhydroxy aldehyde or ketone
• Three main functions:
• energy storage
• an energy source for cellular functions
• glucose
• structural elements in plants and animals
• cellulose & chitin
• Classified into three groups based on the number of sugar units they contain.
• Monosaccharides 
• Disaccharides
• Polysaccharides

Monosaccharides

• These are simple sugars. One polyhydroxy aldhyde or ketone.
• Rarely occur in nature by themselves.
• Usually bonded to an protein, fat or other carbohydrate.
• Glucose is the most abundant sugar in nature.
• The human body maintains a reasonably constant level of 80 to 120 mg of glu- cose per 100 mL of blood.
• Glucose is also the fundamental building block of the most common long-chain carbohydrates.
• Glucose in an aqueous solution exists in an equilibrium between the ring form and the straight-chain form.
• Fructose also forms ring structures when it is in solution.
• Since the carbonyl group is not at the end of the carbon chain, it forms a five-member ring.

Disaccharides

• Contain two monosaccharide units.
• An oxygen bridge between the two monosaccharides holds the two units together.
• Three disaccharides play an important part in the human diet—maltose, lactose, and sucrose.
• Maltose (glucose - glucose)
• germinating grain & digestion of starches
• Lactose (glucose - galactose)
• milk
• Sucrose (glucose - fructose)
• table sugar, fruits, sugar cane, beets, nectar

Polysaccharides

• Many sugar units, up to several million units
• Can be built with several different monosaccharide units
• Glycogen: energy storage 
• Cellulose: gives plants structure
• Starch: supply nearly 3/4ths of the worlds food energy