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78 Cards in this Set
- Front
- Back
scientific method |
1. observation 2. hypothesis 3. experiment 4. theory |
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observation |
facts obtained by observing and measuring events in nature |
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hypothesis |
a statement that explains theobservations |
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experiment |
procedures that test the hypothesis |
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theory |
a model that describes how theobservations occur using experimental results |
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chemical change |
a change in which a new substance is produced *physical change* common sense |
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homogeneous mixture |
the composition is uniform; different parts of the mixture are not visible |
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heterogeneous mixtures |
the composition if not uniform, the different parts of the mixture are visible |
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percent abundance |
percentage of atoms of a particular isotopes in a pure sample of an element |
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isotopes |
atoms with the same number of protons but different number of neutrons |
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mass number |
number of protons and neutrons in the nucleus |
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atomic number |
this number gives the number of protons in n atom |
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a nugget of gold with a mass of 521 g is added to a 50 ml of water. the water level rose to a volume of 77 ml. what is the density? |
77 ml - 50 ml = 27 ml d = m / v d = 521 g / 27 ml d = 19.3 g/ml |
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rules of density |
the heavier the density = sinks the lighter the density = floats |
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# of Protons? |
19 |
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# of electrons? |
19 |
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# of neutrons? |
mass number - atomic number = ? |
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electrons carry a ___________ charge |
negative |
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neutrons carry a __________ charge |
neutral |
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protons carry a _________ charge |
positive |
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alkali metals |
group 1 on the periodic table, excluding hydrogen |
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alkaline earth metals |
group 2 on the periodic table |
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transition metals |
groups 3 - 12 on the periodic table |
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halogens |
group 17 on the periodic table |
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noble gases |
group 18 on the periodic table |
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ionic compound |
compounds composed of cations and anions; for example, aluminum and bromine |
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cation |
formed when an atom loses electrons |
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7244 in scientific notation: a. 72.44 x 10^2 or b. 7.244 x 10^3 |
B |
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nanometers in 9 meters a. 9 x 10^9 or b. 9 x 10^-12 |
A |
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formula for kelvin
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C + 273 |
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formula for atomic weight |
A(A%) + B(B%) |
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molarity: a 16.4 g sample of HF is dissolved in water to give a 2.0 x 10^2 ml of solution the concentration of the solution is? |
find the moles of HF: H = 1.008 (1) = 1.008 F = 18.99 (1) = 18.99 Total: 20 mol weight of HF / moles x solution (16.4 g) / 20 mol (.200 ml) 4.10 |
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Soluble ionic compounds containing the hydroxide ion are called strong _______ |
bases |
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a ______ electron dissociated completes in an aqueous solution |
weak |
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molarity is defined as ______ of solute, per volume of solution in _______ |
moles / liters |
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boyles law |
the volume of a fixed amount of gas inversely proportional to its pressure at constant temperature |
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boyles law a gas sample is heated from -20 C to 57 C and the volume is increased from 2.0 L to 4.50 L. if the initial pressure is 0.140 atm, what is the final pressure? |
P1V1 = P2V2 P1 = 0.140 atm V1 = 2.0 L P2 = ? V2 = 4.50 L 0.0811 atm |
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charles law |
the volume of a fixed amount of gas is directly proportional to its temperature in kelvin at constant pressure |
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charles law a gas sample is held at constant pressure. the gas occupies 3.62 L of volume when the temperature is 21.6 C. determine the temperature at which the volume of the gas is 3.42 l. |
V1T2 = V2T1 V1 = 3.62 L T2 = ? V2 = 3.42 L T1 = 21.6 C (+ 273) = 294.6 k 278 K |
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molar mass of aspirin (C9H804) |
C = 12.01 (9) = 108.9 H = 1.008 (8) = 8.064 0 = 16 (4) = 64 Total = 180.514 g/mol |
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salt in water is a heterogeneous solution a. true b. false |
B |
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acid + base = _______ + water |
salt |
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ph rules (indicates the acidity or basicity of a solution) |
acidic: 3.0 - 6.0 neutral: 7.0 basic: 8.0 - 10 |
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which is not an acid
HCl HNO3 NaOH HBr HF |
NaOH |
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is solute > , = , or < to the amount of solution |
< (less than) |
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avagadros number |
6.022 x 10^23 |
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a sample of ammonia (NH3) has a mass of 43.5 g. how many molecules are in this sample? |
N = 14.01 (1) = 14.01 H = 1.008 (3) = 3.024 Total = 17.034 mol Mass x Moles 43.5 g x (1 g / 17.034 mol) = 0.058706117 ^ x avagadros number 0.058706117 x (6.022 x 10^23) 1.54 x 10^24 |
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how many atoms of hydrogen are present in 7.63 g of ammonia |
N = 14.01 (1) = 14.01 H = 1.008 (3) = 3.024 Total = 17.034 mol 7.63 g / 17.034 mol = 0.4479276 0.4479276 x 3 (H) = 1.34378 1.34378 x (6.022 x 10^23) 8.09 x 10^23 |
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a 7.11 g sample of potassium chlorate was decomposed according to the equation: 2KClO3 --> 2KCl + 3O2 how many moles of oxygen are formed? |
sample x 1 / molar mass x mole ratio sample = 7.11 g molar mass = 1 mol / 122.55 g mole ratio: 3 / 2 *mole ratio is obtained from the coefficients. put the unknown (asked) on top and the known (given) on the bottom* Answer: 0.0870 mol |
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an unknown substance dissolves readily in water (a polar solvent) but not in benzene (a polar solvent). molecules of what type are present in the substance? |
polar |
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a sample of 35.1 g of methane (CH4) gas has a volume of 3.11 L at a pressure of 2.70 atm. calculate the temperature. |
PV = nRT Answer: 2.92 K P = 2.70 atm V = 3.11 L n = 35.1 R = molar mass of CH4 T = ? * |
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what volume of H2O(g) measured at STP is produced by the combustion of 6.27 g of natural gas (CH4) according to the following equation: CH4(g) + 2O2(g) ---> CO2(g) + 2H2O(g) *1 mol of CH4 = 2 Mol H20 **1 mol of gas = 22.4 |
molar mass of CH4: 16 g/mol moles of methane: 6.27 g x (1 mol/ 16g) = 0.391 *0.391 X 2 = 0.78375 **0.78375 x 22.4 = 17.5 L |
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what volume does 40.5 g of N2 occupy at STP |
PV = nRT Answer: 32.4 L P = 1 atm V = ? n = molar mass of N2 R = 0.0821 L T = 273 K |
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at constant volume, temperature and pressure are _______ |
directly proportional |
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which gas has molecules with the greatest average molecular speed of 25 C? |
H2 |
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at STP, 1 mol of Kr gas has a volume of 22.4 L. in liters, what is the volume of 5 mol of Kr at STP? |
1 mol of Kr = 22.4 L 5 mol of Kr x (22.4 L) = 112.0 L |
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how many grams of NaCl are contained in 350mL of a 0.287M solution of sodium chloride |
multiply 0.250M x 0.350L take the answer and multiply by the molar mass of NaCl (58.45) Answer: 5.87 g |
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many of the unusual properties of water are the result of |
hydrogen bonding |
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a surfactant causes water to spread out over a surface. this spreading occurs because the surfactant |
interferes with hydrogen bonding |
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homogenized milk contains finely divided particles that do not settle out rapidly and are not readily filtered. thus, homogenized milk is a _________ |
colloid |
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for a given substance, which of the following will NOT influence how fast it dissolves? temperature amount of agitation molar mass size of the crystals |
molar mass |
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the solubility of a gas in a solvent is affected by |
both temperature and pressure |
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diluting a solution does NOT change which of the following: concentration volume milliliters of solvent moles of solute |
milliliters of solvent |
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which of the following is an example of an ionic compound? CO2 NH3 NaCl N2 |
NaCl |
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a hydrocarbon with a single bond is an ? alkane or alkene |
alkane |
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a hydrocarbon with a double bond is an ? alkane or alkene |
alkene example: H2C [double bond] CH [single] CH3 |
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cycloalkane |
only contain carbon-hydrogen bonds and carbon-carbon single bonds |
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alkyne |
unsaturated hydrocarbons containing a triple bond, including acetylene |
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unsaturated compounds |
organic compounds with double or triple bonds |
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aromaticcompound |
a compoundthat contains the ring structure of benzene <--- example |
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this compound is named ________ |
benzene |
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alpha or beta particle? |
beta particle |
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alpha or beta particle? |
alpha particle |
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a nuclear equation is balanced when |
thesum of the mass numbers and the sum of the atomic numbers of the particles andatoms are the same on both sides of the equation |
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alpha or beta decay? |
alpha decay |
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alpha or beta decay? |
beta decay |
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carbon-11 is a radioactive isotope of carbon. Its half-life is 20minutes. What fraction of the initial number of C-11 atoms in a sample willhave decayed away after 80 minutes? |
divide the time by the half life 80 / 20 = 4 take the inverse square of that number 1/2^4 = 1/16 |
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when 59Cu undergoes positron emission, what is theimmediate nuclear product? |
The mass number of the new nucleus is the same ,but the atomicnumber decreases by 1. Answer: 58Ni |