Portage Chemistry 103 Module 1 Exam Study

3.) (12.5340 - 8.350) / 4.76 + 8.35 =

9.23 (to hundredths place, 8.35)

IONIC CHARGE

= (# of protons) - (# of electrons) = +n or -n

ATOMIC CHARGE

= (# of protons) - (# of electrons) = 0

CHARGE OF A NONMETAL

= (periodic table group # - 8)

CHARGE OF A METAL

= + (periodic table group #)

ATOMIC WEIGHT

# of protons + # of neutrons The atomic weight is the larger number associated with each element in the periodic table.

ATOMIC NUMBER

# of protons = # of electrons

5.) V = M/D = 1000 g / 13.6 g/ml =

73.5 ml (division, density contains only 3 sig figs)

4.) What is the average of 0.1707, 0.1713, 0.1720, 0.1704, and 0.1715? = 0.17118=

0.1712

1.2: METRIC SYSTEM - UNIT CONVERSIONS

1 foot (ft)=12 inches (in) 1 kilogram (kg)=1000 grams (g) 1 pound (lb)=16 ounces (oz) 1 gallon (gal)=4 quarts (qt) 1000 milliliters (ml)=1 liter (L) 100 centigrams (cg)=1 gram (g) 10 decimeters (dm)=1 meter (m)

How many significant figures are there in each of the following numbers?

1.) 0.004035 contains 4 significant figures 2.) 306.2 contains 4 significant figures 3.) 20.70 contains 4 significant figures 4.) 0.3450 contains 4 significant figures 5.) 0.0231 contains 3 significant figures 6.) 45.670 contains 5 significant figures 7.) 0.00034 contains 2 significant figures

1.3: TEMPERATURE CONVERSIONS

1.) 132 oC + 273 = 405 oK 2.) 132 oF - 32 x 1.8 = 55.6 oC + 273 = 328.6 oK 3.) 285 oK - 273 = 12 oC 4.) 60 oC x 1.8 + 32 = 140 oF 5.) 85 oF - 32 x 1.8 = 29.4 oC 6.) 52 oC + 273 = 325 oK 7.) 32 oC x 1.8 + 32 = 89.6 oF 8.) 412 oK - 273 = 139 oC x 1.8 + 32 = 282.2 oF

2.) 7.54 / 2.390 + 1.53 - 2.810 =

1.87 (to hundredths place, 1.53

6.) D = M/V = 155 g / 50 ml =

3.1 g/ml (division, volume contains only 2 sig figs)

1.) (5.625 + 8.15) x 2.34 + 3.2 =

35.4 (to tenths place, 3.2)

The original quantity and unit (to be converted) are multiplied by a conversion factor (which is a fraction made up as follows): New unit (on top) / Old unit (on bottom)

48 ounces = ? pounds 48 o z × 1 p o u n d / 16 o z = 3 p o u n d s 4 kilograms = ? grams 4 Kg X 1000 grams/1kg = 4000 grams 1.) 656 cm x 1 m / 100 cm = 6.56 m 2.) 20 gal x 4 qt / 1 gal = 80 qts 3.) 7820 ml x 1 liter / 1000 ml = 7.82 liters 4.) 36 g x 1000 mg / 1 g = 36000 mg 5.) 25.3 g x 10 dc / 1 g = 253 dg 6.) 6.2 m x 1000 mm / 1 m = 6200 mm 7.) 725 l x 1000 ml / 1 liter = 725,000 ml 8.) 56 ft x 12 in / 1 ft = 672 in

Compounds

A compound is an intimate combination of two or more elements in which the elements become attached to one another. Compounds can be recognized by their scientific name, which does not appear on the table of elements but contains the name (or part of the name) of two or more elements. Table salt is actually a compound called sodium chloride, and the names of two elements sodium and chlorine appear in the name of this compound.

Heterogeneous mixtures

A heterogeneous mixture is a combination of two or more elements or compounds, which appears (to the eye) to be more than one layer or material. For instance, when sand (a compound) is added to water (actually the compound hydrogen oxide), the sand settles in one layer on the bottom with the water forming another layer on top.

Homogeneous mixtures (also called solutions)

A homogeneous mixture (solution) is a combination of two or more elements or compounds, which appears (to the eye) to be one layer or material. For instance, when salt (a compound) is added to water (actually the compound hydrogen oxide), the two materials mix with the salt dissolving (disappearing) to make a solution.

SILVER

Ag

ALUMINUM

Al

1.9: ATOMIC STRUCTURE

All matter is composed of atoms, the most basic unit. You can think of an atom like our solar system with most its mass concentrated at the center and smaller objects orbiting around the central mass. The large central mass of the atom is called the nucleus and contains two types of particles called protons and neutrons. The protons have a positive (+) charge; the neutrons have no charge. The low-mass particles orbiting around the nucleus are called the electrons; they have a negative (-) charge.

ARSENIC

As

ARGON

Ar

GOLD

Au

BORON

B

BARIUM

Ba

BERYLLIUM

Be

BISMUTH

Bi

BROMINE

Br

CARBON

C

CALCIUM

Ca

CADMIUM

Cd

Is only one substance, layer, or color seen when I look at the material?

Yes - The material is a solution. No - The material is a heterogeneous mixture.

Water undergoes electrolysis to form hydrogen gas and oxygen gas

Chemical

Cr+3

Chromium (III)

Cr+6

Chromium (VI)

CHLORINE

Cl

COBALT

Co

Cu+1

Copper (I)

CHROMIUM

Cr

COPPER

Cu

The following equation is used to calculate density if you know the mass (in grams) and the volume (in milliliters).

D (g/ml) = M(g) / V(ml) 1.) 35.6 ml = V 1.86 g/ml = D find M = D x V = 1.86 x 35.6 = 66.2 grams 2.) 13.6 g/ml = D 1000 g = M find V = M / D = 1000 / 13.6 = 73.5 ml 3.) 200 ml = V 620 g = M find D = M / V = 620 g / 200 ml = 3.10 g/ml

HYDROGEN

H

1.4: DENSITY

Density represents the mass of a substance in a unit volume of that substance. The density of most solids or liquids is expressed in the unit grams per milliliter (or g/ml).

1.7: PHYSICAL AND CHEMICAL CHANGES

Examples of physical changes are the processes of: melting freezing boiling (or evaporation) condensation dissolving Examples of chemical changes are the processes of: burning (or combustion) - heat/light evolved rusting (or oxidizing) - color change (gray steel to red rust) an explosion - gas evolved baking

In multiplication or division calculations, the result should be rounded off so as to contain the same number of significant figures as the measurement with the least number of significant figures.

Examples: 128.61 / 51.20 = 2.51191 = 2.512 (round off to 4 significant figures because of 51.20) 54.06 x 17.0 = 919.02 = 919 (round off to 3 significant figures because of 17.0)

The appropriate number of significant figures must be reported in any answer resulting from a calculation. The rules for reporting the correct number of significant figures in an answer depends on whether the calculation involved addition/subtraction or multiplication/division. In addition or subtraction calculations, the result should be rounded off (more about that later) so that it has the same number of decimal places as the measurement having the fewest decimal places (counting from left to right).

Examples: 8.612 + 4.51 + 0.20 + 3.9 = 17.222 = 17.2 (round off to tenths place because of 3.9) 47.60 - 23. = 24.60 = 25 (round off to the unit's place because of 23.)

FLUORINE

F

IRON

Fe

HELIUM

He

MERCURY

Hg

IODINE

I

Rules for rounding off numbers: Wait until all operations (in a multiple-step problem) have been done before rounding off the final answer.

If the digit to be dropped is greater than 5, the last retained digit is increased by one. For example, 12.6 is rounded to 13. If the digit to be dropped is less than 5, the last remaining digit is left as it is. For example, 12.4 is rounded to 12. If the digit to be dropped is 5, and if any digit following it is not zero, the last remaining digit is increased by one. For example, 12.51 is rounded to 13. If the digit to be dropped is 5 and is followed only by zeroes, the last remaining digit is increased by one if it is odd but left as it is if even. For example, 11.5 is rounded to 12, 12.5 is rounded to 12.

Fe+2

Iron (II)

Fe+3

Iron (III)

isotopes

Isotopes of an element have the same number of protons and electrons as one another, but they have differing numbers of neutrons. This means that they have the same atomic number and charge (0) but different mass numbers.

POTASSIUM

K

K to °C(°C and K differ by 273)

K (larger) - 273 = °C (smaller)

LITHIUM

Li

Is the name of the material on the list of elements?

Yes - The material is an element. No - The material is a compound, solution, or heterogeneous mixture.

ZINC

Zn

Mn+2

Manganese (II)

Mn+4

Manganese (IV)

Mn+7

Manganese (VII)

1.8: CHANGES IN TEMPERATURE

Melting ice to liquid water requires heat to be added, so process is endothermic. Condensing steam to liquid water requires heat to be extracted, so the process is exothermic. Cooling liquid water from 25° to 20° requires heat to be extracted, so the process is exothermic. Burning natural gas gives off heat (and light as a flame), so process is exothermic. Applying an instant cold pack from an athletic trainer's kit to the bruised knee of a soccer player extracts heat from the knee, so the process is exothermic.

MAGNESIUM

Mg

MANGANESE

Mn

NITROGEN

N

SODIUM

Na

NEON

Ne

NICKEL

Ni

OXYGEN

O

PHOSPHORUS

P

LEAD

Pb

PLATINUM

Pt

1.5: SIGNIFICANT FIGURES

Rules for determining significant figures in a number: All non-zero digits are significant. All zeros between or following non-zero numbers are significant. Zeros to the left of a decimal or preceding other non-zero numbers are not significant. 4326.7 - This number contains 5 significant figures (in bold). 400.70 - This number contains 5 significant figures (in bold). 0.3267 - This number contains 4 significant figures (in bold). 0.0070 - This number contains 2 significant figures (in bold). 0.5070 - This number contains 4 significant figures (in bold).

SULFUR

S

ANTIMONY

Sb

SILICON

Si

TIN

Sn

STRONTIUM

Sr

1.10: CHEMICAL NAMES - 1. Binary Ionic Compounds

The name of an element is slightly modified when naming it as part of a binary (containing only two elements: a metal and a nonmetal) compound since the metal has become a positively charged ion (cation) and the nonmetal has become a negatively-charged ion (anion). Metal name + nonmetal stem + "ide"

1.1 EXPONENTIAL NUMBERS

The speed of light is 186,000 miles per second. This is 1.86 x 105 (in exponential form) The diameter of an E. coli cell is 0.00000080 meters = 8.0 x 10-7 (in exponential form) 4950000000. A number larger than one will have a positive exponent. Move the decimal point nine places to the left to give 4.95 x 109 0.00000000000056 A number smaller than one will have a negative exponent. Move the decimal point 13 places to the right to give 5.6 x 10-13 1.) 0.00000456 = smaller than 1 = negative exponent, move decimal 6 places = 4.56 x 10-6 2.) 2.63 x 107 = positive exponent = larger than 1, move decimal 7 places = 26300000. 3.) 7800000. = larger than 1 = positive exponent, move decimal 6 places = 7.8 x 106 4.) 8.26 x 10-5 = negative exponent = smaller than 1, move decimal 5 places = 0.0000826 5.) 5.38 x 10-3 = negative exponent = smaller than 1, move decimal 3 places = 0.00538 6.) 0.000673 = smaller than 1 = negative exponent, move decimal 4 places = 6.73 x 10-4 7.) 3.82 x 104 = positive exponent = larger than 1, move decimal 4 places = 38200. 8.) 623000000. = larger than 1 = positive exponent, move decimal 8 places = 6.23 X 108

Elements

There are over 100 elements that are the basic materials from which all other classes of matter are derived. These elements are pure substances containing no other element and are listed in the periodic table of the elements

TITANIUM

Ti

URANIUM

U

Are the names (or part of the names) of two elements present in the scientific name of the material?

Yes - The material is a compound. No - The material is a solution or a heterogeneous mixture.

TUNGSTEN

W

Are two or more substances, layers, or colors seen when I look at the material?

Yes - The material is a heterogeneous mixture.

The prefixes kilo (= 1000), milli (= 1/1000), centi (= 1/100), and deci (= 1/10)

are used with any metric unit, such as grams (weight), liters (volume), and meters (distance).

Cl-

chloride

Thermochemistry

he study of how much heat is involved in a chemical change.

N-3

nitride

O-2

oxide

S-2

sulfide

Calorimetry

the study of how much heat is involved in a temperature or physical change

°C to K(°C and K differ by 273)

°C (smaller) + 273 = K (larger)

°C to °F(Multiply by 1.8, and add 32)

°C X 1.8 + 32 = °F

°F to °C(Subtract 32, and divide by 1.8)

°F - 32 / 1.8 = °C