Miscellaneous Chemistry (Trimester A Review)

Question 1

(Topic 00) Accuracy

Answer 1

How close the measured value is to the actual value of the quantity.

Question 2

(Topic 00) Precision

Answer 2

How close two or more measurements of the same quality are to one another.

Question 3

(Topic 00) When multiplying or dividing, limit the answer to the same number of significant figures that appear in the original data with the fewest number of…

Answer 3

significant figures.

Question 4

(Topic 00) When adding or subtracting, limit the answer to the same number of significant figures that appear in the original data with the fewest number of…

Answer 4

decimal places.

Question 5

(Topic 01) Democritus

Answer 5

First theorized the atom (“atomos”).

Question 6

(Topic 01) Antoine Lavoisier

Answer 6

Law of Conservation of Mass; mass of reactants equal mass of products.

Question 7

(Topic 01) Joseph Proust

Answer 7

Law of Definite Proportions; different pure samples of the same compound always contain the same proportions of each element by mass.

Question 8

(Topic 01) John Dalton’s Four Postulates

Answer 8

1. Each element is composed of tiny particles called atoms.
2. All atoms of a given element are identical, and all atoms of different elements are different (incorrect; isotopes exist)
3. Atoms are not created or destroyed in chemical reactions. They are dissociated, combined, or recombined.
4. Compounds are formed when atoms of different elements combine with one another, a given compound always contains the same relative numbers and types of atoms.

Question 9

(Topic 01) J.J. Thompson

Answer 9

Discovered electrons via cathode ray tube experiments.

Question 10

(Topic 01) Earnest Rutherford

Answer 10

Discovered the atomic nucleus via gold foil experiments.

Question 11

(Topic 01) Equation for Average Atomic Mass

Answer 11

avg. atomic mass = (m#₁)(%₁) + (m#₂)(%₂) + (m#₃)(%₃) + …

Question 12

(Topic 01) Atomic Radius Periodic Table Trend

Answer 12

Atomic radius decreases as you move up and to the right on the periodic table;

Large radii bottom and to left
Small radii top and to right

Question 13

(Topic 01) First Ionization Energy (IE) Periodic Table Trend

Answer 13

First IE increases as you move up and to the right on the periodic table;

Low IE bottom and to left
High IE top and to right

Question 14

(Topic 01) Electronegativity Periodic Table Trend

Answer 14

Electronegativity increases as you move up and to the right on the periodic table;

Low electronegativity down and to left
High electronegativity up and to right

Question 15

(Topic 01) Avogadro’s Number

Answer 15

6.022*10^23

Question 16

(Topic 01) Percent Yield

Answer 16

% yield = (actual yield/theoretical yield)*100

Question 17

(Topic 01) Steps to Finding Empirical Formula

Answer 17

1. Assume you have a 100 g sample.
2. Convert each element (their given percentages) to moles.
3. Divide the number of moles of each element by the smallest value for moles calculated in the previous step.

Question 18

(Topic 01) Finding Molecular Formula from Empirical Formula

Answer 18

1. Molar mass/empirical formula mass = multiplier for empirical formula.
2. Multiply each subscript number in empirical formula by the multiplier calculated previously to find the molecular formula.

Question 19

(Topic 01) Difference Between Molecular and Empirical Formulas

Answer 19

Molecular Formula: Chemical formula with actual number of each type of atom in molecule (ex. N2H4)

Empirical Formula: Chemical formula with relative number of each type of atom in molecule; a ratio of elements in molecule in simplest form (ex. NH2).