quiz 1 Flashcards
what are the two characteristics of measurements that scientists are concerned with?
accuracy and precision
accuracy
how correct the measurement is. When measuring something, it is always desirable to get the “right” answer!
precision
how close a set of measurements of the same thing are to each other.
density
the ratio of a substance’s mass to its volume. It can be expressed by the equation d = m / v
(mass / volume)
finding mass of a solid
the amount of material in the sample.
- Many solids can be placed directly on the pan of a balance to determine their mass
finding mass of a liquid
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)
volume
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
meniscus
the low point in the lens-shaped surface of the liquid in a cylinder
Ammonia (NH3)
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.
Calcium ion (Ca2+)
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
Carbon dioxide (CO2) and hydrogen carbonate ion (HCO3 -1)
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
Chloride ion (Cl -1)
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.
Copper ion(II) (Cu2+)
- 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.
Iron(II) ion (Fe2+)
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
Phosphate ion (PO4 3-) and related phosphorus-containing ions
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
Sodium ion (Na1+)
present in the body to help maintain proper fluid balance.
- Imbalances can be due to dehydration, fluid retention, and heart or kidney problems.
five types of chemical reactions that are commonly used to describe many of the chemical changes that occur around us every day
- Combination or synthesis reactions
- Decomposition reactions
- Single replacement reactions
- Double replacement reaction
- two types of double replacement reactions:
a. Precipitation reactions
b. Neutralization reactions - Combustion reactions
Combination or synthesis reactions
two elements or compounds combine to form one compound.
Decomposition reactions
one compound breaks up into two or more elements or compounds.
Single replacement reactions
where an element and a compound form a different element and different compound.
Double replacement reactions
where two compounds make two different compounds. There are two types of double replacement reactions:
a. Precipitation reactions
b. Neutralization reactions
DR: Precipitation reactions
where two compounds form two different compounds, where at least one of the products is a solid.
DR: Neutralization reactions
where an acid and a base form water and a salt (anion + cation).
Combustion reactions
where a hydrogen-and-carbon-and-maybe-oxygen- containing compound burns in oxygen to form carbon dioxide and water.
Chemical reactions can be distinguished from physical changes at the macroscopic level if one of the following four observations are noted:
a gas is produced, a pre- cipitate (solid) forms, a color change occurs and a new color is observed, and a temperature change occurs.
four common gasses
Hydrogen, oxygen, and carbon dioxide, and ammonia
ammonia
- 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.
when is hydrogen present?
Hydrogen is present if the flame extinguishes, frequently with a very faint whistling sound
when is carbon dioxide present?
Carbon dioxide will extinguish the flame with no sound.
when is oxygen present?
Oxygen’s presence will make the flame flare up and burn brighter.
Carbonate compounds usually decompose to give
carbon dioxide
hydroxide compounds often produce
hydrogen gas.
solubility rules: soluble
Soluble Compounds (dissolve in water):
- Sodium, potassium, and ammonium compounds
- Acetates and nitrates
- Chlorides, bromides, iodides (halides); exceptions: Lead(II), mercury(I), and silver halides
- Sulfates; exceptions: Calcium, strontium, barium, and lead(II)
solubility rules: insoluble
- Carbonates, chromates, and phosphates; exceptions: Sodium, potassium, and ammonium
- Hydroxide; exceptions: Sodium, potassium, and barium
- sulfides; exceptions: Sodium, potassium, ammonium, and calcium
An ion
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).
common cations and anions
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-
Ionic compounds
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.
testing for cations
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)
There are only three anions you can have in your compound in today’s experiment and they are…
they are all halides (Cl–, Br–, and I–)
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?
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.
the halide test
- 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.
halide test process
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
RAMP model
Recognize the hazard
Assess the risks of the hazard
Minimize the risks of the hazards
Prepare for emergencies caused by uncontrolled hazards
corrosion
corrosion
- skin corrosive/burns
- eye damage
- corrosive to metals
exclamation mark
- irritant
- skin sensitizer
- acute toxicity
- narcotic effects
- respiratory tract irritant
- hazardous to ozone layer (non-mandatory)
exploding bomb
- explosives
- self-reactive
- organic peroxides
skulls and crossbones
acute toxicity (fatal or toxic)
flame
- flammables
- pyrophobics
- self heating
- emits flammable gas
- self-reactives
- organic peroxides
gas cylinder
- gases under pressure
environment
aquatic toxicity
health hazards
- carcinogen
- mutagenicity
- reproductive toxicity
- respiratory sensitizer
- target organ toxicity
- aspiration toxicity
flame over circle
oxidizers
density
mass / volume
