quiz 1

Question 1

what are the two characteristics of measurements that scientists are concerned with?

Answer 1

accuracy and precision

Question 2

accuracy

Answer 2

how correct the measurement is. When measuring something, it is always desirable to get the “right” answer!

Question 3

precision

Answer 3

how close a set of measurements of the same thing are to each other.

Question 4

density

Answer 4

the ratio of a substance’s mass to its volume. It can be expressed by the equation d = m / v
(mass / volume)

Question 5

finding mass of a solid

Answer 5

the amount of material in the sample.

- Many solids can be placed directly on the pan of a balance to determine their mass

Question 6

finding mass of a liquid

Answer 6

the liquid must be placed in a pre-weighed container, and the container must then be re-weighed with the liquid in it
(finding mass by difference)

Question 7

volume

Answer 7

the amount of space a sample occupies.

• If the sample is a liquid, its volume can be measured directly by placing it in a calibrated container
• read the meniscus
• If the sample is a rectangular solid, its volume can be found by measuring the length, width, and height of the object, and multiplying the three together: V = L × W × H.
• If the solid has an irregular shape, we can find its volume by immersing it in a known amount of liquid, and determining the volume of liquid displaced by the solid. (finding the volume by displacement) V2 - V1

Question 8

meniscus

Answer 8

the low point in the lens-shaped surface of the liquid in a cylinder

Question 9

Ammonia (NH3)

Answer 9

a waste product, forms by protein digestion and from intestinal bacteria.

• Ammonia can build up in the blood if there are kidney problems, Reye’s syndrome, liver disease, and some genetic diseases.
• Ammonia can cross the blood–brain barrier, leading to mental and neurological changes that may result in death.

Question 10

Calcium ion (Ca2+)

Answer 10

needed for bones and teeth; it is also necessary for muscle contraction.
- High or low calcium levels can be present in diseases of the thyroid and parathyroid glands

Question 11

Carbon dioxide (CO2) and hydrogen carbonate ion (HCO3 -1)

Answer 11

present in the body to help maintain the acid–base level, or pH, of your body.
- pH imbalances can be caused by electrolyte imbalance, kidney disease, hypertension, and the use of some medications

Question 12

Chloride ion (Cl -1)

Answer 12

present in blood and in extracellular fluid.

• It helps to maintain the body’s pH and regulates fluid levels.
• Imbalances can result from dehydration or from acidosis (body pH decreases) or alkalosis (body pH rises).
• Changes in chloride often mirror those of sodium.

Question 13

Copper ion(II) (Cu2+)

Answer 13

• plays an important role in enzymes that help regulate iron metabolism, form connective tissue, and produce energy.
• Wilson’s disease, an inherited disease associated with excess storage of copper, causes liver and neurological damage.

Question 14

Iron(II) ion (Fe2+)

Answer 14

needed to form red blood cells.

• It is also a critical part of hemoglobin, the protein that carries oxygen throughout the body.
• Low levels lead to anemia, while high levels can damage the heart, liver, and pancreas

Question 15

Phosphate ion (PO4 3-) and related phosphorus-containing ions

Answer 15

bind with calcium and magnesium to strengthen bones and teeth, and helps to regulate the body’s pH.
- imbalances may signal kidney or gastrointestinal problems

Question 16

Sodium ion (Na1+)

Answer 16

present in the body to help maintain proper fluid balance.

- Imbalances can be due to dehydration, fluid retention, and heart or kidney problems.

Question 17

five types of chemical reactions that are commonly used to describe many of the chemical changes that occur around us every day

Answer 17

1. Combination or synthesis reactions
2. Decomposition reactions
3. Single replacement reactions
4. Double replacement reaction
   - two types of double replacement reactions:
   a. Precipitation reactions
   b. Neutralization reactions
5. Combustion reactions

Question 18

Combination or synthesis reactions

Answer 18

two elements or compounds combine to form one compound.

Question 19

Decomposition reactions

Answer 19

one compound breaks up into two or more elements or compounds.

Question 20

Single replacement reactions

Answer 20

where an element and a compound form a different element and different compound.

Question 21

Double replacement reactions

Answer 21

where two compounds make two different compounds. There are two types of double replacement reactions:

a. Precipitation reactions
b. Neutralization reactions

Question 22

DR: Precipitation reactions

Answer 22

where two compounds form two different compounds, where at least one of the products is a solid.

Question 23

DR: Neutralization reactions

Answer 23

where an acid and a base form water and a salt (anion + cation).

Question 24

Combustion reactions

Answer 24

where a hydrogen-and-carbon-and-maybe-oxygen- containing compound burns in oxygen to form carbon dioxide and water.

Question 25

Chemical reactions can be distinguished from physical changes at the macroscopic level if one of the following four observations are noted:

Answer 25

a gas is produced, a pre- cipitate (solid) forms, a color change occurs and a new color is observed, and a temperature change occurs.

Question 26

four common gasses

Answer 26

Hydrogen, oxygen, and carbon dioxide, and ammonia

Question 27

ammonia

Answer 27

- It can often be identified by its smell, which may remind people of a beauty salon—perms and hair color often contain ammonia or ammonium compounds. - Ammonia can more safely be detected by wetting a piece of red litmus paper and holding it over the solid or solution that may contain ammonia. - The ammonia reacts to turn the litmus blue; the water simply makes the color change more obvious.

Question 28

when is hydrogen present?

Answer 28

Hydrogen is present if the flame extinguishes, frequently with a very faint whistling sound

Question 29

when is carbon dioxide present?

Answer 29

Carbon dioxide will extinguish the flame with no sound.

Question 30

when is oxygen present?

Answer 30

Oxygen’s presence will make the flame flare up and burn brighter.

Question 31

Carbonate compounds usually decompose to give

Answer 31

carbon dioxide

Question 32

hydroxide compounds often produce

Answer 32

hydrogen gas.

Question 33

solubility rules: soluble

Answer 33

Soluble Compounds (dissolve in water): 1. Sodium, potassium, and ammonium compounds 2. Acetates and nitrates 3. Chlorides, bromides, iodides (halides); exceptions: Lead(II), mercury(I), and silver halides 4. Sulfates; exceptions: Calcium, strontium, barium, and lead(II)

Question 34

solubility rules: insoluble

Answer 34

1. Carbonates, chromates, and phosphates; exceptions: Sodium, potassium, and ammonium 2. Hydroxide; exceptions: Sodium, potassium, and barium 3. sulfides; exceptions: Sodium, potassium, ammonium, and calcium

Question 35

An ion

Answer 35

a chemical species that carries an electrical charge. - Neutral atoms get charged by either gaining or losing electrons. - If a neutral atom gains an extra electron it will become negatively charged (anions) - loss of an electron will cause the neutral atom to become positively charged (cations).

Question 36

common cations and anions

Answer 36

``` calcium ion = Ca2+ barium ion = Ba2+ chloride ion = Cl- sulfide ion = S2- sodium ion = Na+ copper(II) ion = Cu2+ bromide ion = Br- oxide ion = O2- ```

Question 37

Ionic compounds

Answer 37

made up of two separate and somewhat independent chemical species, a cation and an anion. - The cation is usually a metal ion - anion is almost always a nonmetal. - CaCl2 dissolved in water gives Ca2+ + Cl- + Cl- - In a compound, the sum of the positive charges must be balanced by the sum of the negative charges.

Question 38

testing for cations

Answer 38

In this experiment, you will be given photos of the flame test results for six different cations: Li+, Na+, K+, Ca2+, Sr2+, Ba2+ - You will also test for the cations by reacting them with three different reagents and observing which cations will form a precipitate with the reagents: Strontium ion + ammonium carbonate → cloudy white solution (a precipitate) Lithium ion + ammonium carbonate → clear solution (no precipitate)

Question 39

There are only three anions you can have in your compound in today’s experiment and they are...

Answer 39

they are all halides (Cl–, Br–, and I–)

Question 40

Consider that both lithium and strontium give a red color in the flame test. If you have an unknown that gives a red color, how do you determine which metal ion is in the unknown?

Answer 40

Well, from the data above you would test your unknown by reacting it with ammonium carbonate. If no precipitate results it must be lithium, while a precipitate would indicate the presence of strontium.

Question 41

the halide test

Answer 41

- When you do the halide test you will form the halogen in an aqueous (water based) solution. - Water is a polar solvent - The halogens you will be forming are nonpolar, so they are not very soluble in water, but you will be able to distinguish a difference in the color of the solution when the halogens are formed.

Question 42

halide test process

Answer 42

2 Cl– chloride ions colorless -> bleach -> Cl2 chlorine faint yellow 2 Br– bromide ions colorless -> bleach -> Br2 bromine orange/brown 2 I- iodide ions colorless -> bleach -> I2 iodine purple/dark purple/black

Question 43

RAMP model

Answer 43

Recognize the hazard Assess the risks of the hazard Minimize the risks of the hazards Prepare for emergencies caused by uncontrolled hazards

Question 44

corrosion

Answer 44

corrosion - skin corrosive/burns - eye damage - corrosive to metals

Question 45

exclamation mark

Answer 45

- irritant - skin sensitizer - acute toxicity - narcotic effects - respiratory tract irritant - hazardous to ozone layer (non-mandatory)

Question 46

exploding bomb

Answer 46

- explosives - self-reactive - organic peroxides

Question 47

skulls and crossbones

Answer 47

acute toxicity (fatal or toxic)

Question 48

flame

Answer 48

- flammables - pyrophobics - self heating - emits flammable gas - self-reactives - organic peroxides

Question 49

gas cylinder

Answer 49

- gases under pressure

Question 50

environment

Answer 50

aquatic toxicity

Question 51

health hazards

Answer 51

- carcinogen - mutagenicity - reproductive toxicity - respiratory sensitizer - target organ toxicity - aspiration toxicity

Question 52

flame over circle

Answer 52

oxidizers

Question 53

density

Answer 53

mass / volume