CHEM 110 - MIDTERM #1 Flashcards
What kind of science is Chemistry?
Central Science - it joins together all the sciences (physics & biology)
What is the scientific method?
Systematic approach to research (observation -> representation -> interpretation)
What is the difference between law and theory?
Law: concise statement of a relationship between phenomena that is always the same under the same conditions (F = ma)
Theory: unifying principle that explains a body of facts and/or those laws based on them (atomic theory)
Chemistry is the study of ______.
Matter
What is a substance?
Form of matter that has a definite composition and distinct properties (Ex: H2O)
What is a mixture?
Combination of 2 or more substances in which the substances retain their distinct identities
Difference between homogenous mixture & heterogenous mixture?
Homogenous mixture: mixture composition is the same throughout
Hetereogenous mixture: composition is not uniform throughout
What is are some examples of a homogenous mixture?
Air, Sea Water, Wine
What are some examples of heterogenous mixtures?
Chicken noodle soup, sand, oil & water
What is the physical means of separating a mixture?
Does not change the chemical composition of a substance (ie. distillation, ice melting, magnet)
What is the chemical means of separating a mixture?
Changing the chemical composition or identity of the substance(s) involved
An element cannot be separated into simpler substances by _______ means.
chemical
What is a compound?
A substance composed of atoms of two or more elements chemically united in fixed proportions
A compound can be separated into their pure elements by _____ means.
Chemical
What’s the difference between a mixture and a substance?
Mixture: combination of substances that can be separated by physical methods to form substances
Substances: form of matter with distinct properties composted of compounds and elements
Compounds can be separated via chemical methods to form ____.
Elements
3 States of Matter
Solid: dense shape
Liquid: more degrees of freedom
Gas: no shape, but occupy space all throughout
What is an example of chemical change?
Hydrogen burning in air to form water
What’s the difference between extensive and intensive properties?
Extensive: dependent on amount of matter
Intensive: does NOT dependent on matter
What are examples of extensive properties?
Mass, volume, length
What are examples of intensive properties?
Density, Color, Temperature
What is matter?
Anything that occupies space and has mass
What is weight?
Force that gravity exerts on an object
What SI unit measures the amount of substance?
Mole (mol)
Kilo-
1000 (10^3)
Milli-
1/1000 (10^-3)
Micro-
1/(10^6)
deci-
1/10 (10^-1)
centi-
1/100 (10^-2)
nano-
10^-9
mega-
10^6
pico-
10^-12
What is volume?
SI derived unit for volume is cubic meter (m^3) where 1 mL = 1 cm^3
What is density?
SI derived unit for density is kg/m^3
D = mass/volume
What are the units for density?
g/mL or g/cm^3
How do we find Kelvin (K) from using Celsius?
K = C + 273.15
What is 0 Celsius in Kelvin?
273.15
How do we find the degrees in Fahrenheit?
F = 9/5 x C + 32
What is scientific notation?
A convenient way of showing the # of significant figures in a value
When you multiply you ___ exponents.
add
When you divide exponents, you ___ exponents.
subtract
What are significant figures?
Any digit that is not zero ~ provides uncertainty and accuracy of a measurement
What is the rule for addition/subtraction with # of sig figs?
The answer cannot have more digits to the right of the decimal point than any of the original numbers (83.3333 + 1.1 = 90.4)
What is the rule for multiplication/division of sig figs?
The # of sig figs must be set by the original number that has the smallest number of sig figs (4.51 + 8.7777777 = 16.6)
What is the difference between accuracy and precision?
Accuracy: how close a measurement is to the true value
Precision: how close a set of measurements are to each other
Give an example of a compound
Sugar, water
Water boiling is an example of ___ change
physical
fertilizers help to increase agricultural production is an example of ____ change
chemical
the flashlight beam slowly gets dimmer and finally goes out is an example of ___ change
chemical
What is Dalton’s Atomic Theory?
1) Elements are composed of atoms
2) All atoms of an element are identical, have same size, mass and chemical properties
3) Compounds are composed of atoms of more than one element
4)A chemical reaction is the rearrangement of atoms (not creation or destruction - law of conservation of mass)
What is the law of conservation of mass?
Mass is not created or destroyed
What is Dalton’s Law of Multiple Proportions?
If 2 elements form more than one compound - the ratio of the masses of the 2nd element can be reduced to whole numbers
What was the finding of Rutherford’s Experiment (1908)?
1) Atoms positive charge is concentrated in the nucleus
2) Protons have an opposite charge (+) of an electron (-)
3) Mass of a proton = 1840 x mass of e- (1.67 x 10^-24 g) = protons are bigger than electrons
What is the atomic number (Z)?
number of protons in a nucleus and determines the identity of an element
What is the mass number (A)?
number of protons + neutrons
What are isotopes?
Atoms of the element with different numbers of neutrons in their nuclei
What is the first group and respective charge in the period table?
Alkali Metals (+1)
What is the second group of the periodic table with their respective charge?
Alkaline Earth Metals (+2)
What is the name of the 3rd-12th group in the periodic table?
Transition metals (varying charges)
What is the name of the 7th group of the periodic table and their respective charges?
Halogens (-1)
What is the name of the last group of the periodic table?
Noble gases
What is the difference between a period and a group?
period = row in the periodic table
group = column in the periodic table
What is a molecule?
Aggregate of 2 or more atoms held by chemical forces
What is an example of a diatomic molecule?
N2, H2, CO, HCl (2 atoms)
What is an example of a polyatomic molecule?
O3, CH4 (more than 2 atoms)
What is an ion?
Atom(s) with a net positive or negative charge
What are the two types of ions?
Anion and cation
What is the difference between cation and anions?
Cation: net positive charge (lose an electron)
Anion: net negative charge (gain an electron)
What is an example of a monatomic ion?
Na+, Cl-
What are the two types of formulas and what are their differences?
Molecular (exact number of atoms of each element in the smallest unit of a substance) & empirical (simplest whole number ratio of atoms in a substance)
An example of molecular and empirical formula
C6H12O6 (molecular)
CH2O (empirical)
What are ionic compounds held together by?
Electrostatic forces (+) and (-) charges
Ionic compounds are generally formed with a ____ and ____
metal, nonmetal
What is an example of an ionic compound?
Na+Cl-
What is the chemical nomenclature of ionic compounds?
The anion (nonmetal), add “‘-ide” to element name
What is the chemical name for K2O?
Potassium oxide
How do we name transition metal ionic compounds?
Indicate the charge on metal with roman numerals
How do we name FeCl2?
Iron (II) chloride
Name Monatomic Atom for S?
Sulfide
Name Monatomic Atom for N?
Nitride
Name Monatomic Atom for P?
Phosphide
What is an inorganic cation?
NH4 (ammonium)
Cu(NO3)2 name?
Copper (II) nitrate
KH2PO4 name?
Potassium dihydrogen phosphate
Calcium phosphate formula?
Ca3(PO4)2
What do molecular compounds consist of?
Nonmetals/nonmetals + metalloids
(they are held together by covalent bonds and made up of discrete, individual molecules)
Common molecular compound?
H2O, CH4, NH3
____ compounds use Greek prefixes & the last element ends in ___ for chemical nomenclature
Molecular, -ide
1
Mono-
2
Di-
3
Tri-
4
Tetra-
5
Penta-
6
Hexa-
7
Hepta
9
Nona-
Deca-
10
NF3 name?
Nitrogen trifluoride
N2O name?
dinitrogen monoxide
SiCl4 name?
Silicon tetrachloride
P4O10 name?
Tetraphosphorus Decoxide
What is an acid?
Substance that yields H+ ions when dissolved in water
HF name?
hydrofluoric acid
HCl name?
Hydrochloric acid
HBr name?
Hydrobromic acid
HI name?
hydroiodic acid
HCN name?
hydrocyanic acid
H2S name?
Hydrosulfuric acid
What is an oxoacid?
An acid that contains hydrogen, oxygen, and another element
Examples of oxoacids?
Nitric acid (HNO3), Carbonic Acid (H2CO3), Phosphoric acid (H3PO4)
H2SO4 name?
Sulfuric acid (Oxoacid)
HClO3- name?
Chloric Acid (Oxoacid)
Naming Oxoanions?
1) Anion ends in “-ate” when the H ions are removed from the “ic” acid
2) Anion ends in “ite” when the H ions are removed from the “-ous” acid
3) Number of H atoms present are indicated with anion names (dihydrogen phosphate H2PO4)
HClO4 name?
Perchloric acid
HClO3 name?
Chloric acid
HClO2 name?
Chlorous acid
HClO name?
Hypochlorous acid
Why does the nomenclature vary with perchloric acid, chloric acid, chlorous acid and hypochlorous acid?
of oxygens vary, corresponding anion vary
H3PO3 name?
Phosphorous acid
HIO4 name?
Periodate
What is a base?
A substance that yields hydroxide ions (-OH) when dissolved in water
NaOH name and ID?
Sodium hydroxide, base
What is a hydrate?
A compound that has a specific number of water molecules attached to them
LiCl x H2O name and ID?
Lithium chloride monohydrate
BaCl2 x 2H2O name and ID?
Barium chloride dihydrate
H2O name?
dihydrogen monoxide
CaO name?
Calcium oxide
Simplest type of organic compound?
Hydrocarbon
Protons and neutrons are ____ than electrons
larger in mass (same with each other)
Mg(HCO3)2 name?
Magnesium bicarbonate
HBrO4 name?
Perbromic acid
HrBrO3 name?
Bromic acid
HBrO2 name?
Bromous acid
HBrO name?
Hypobromous acid
HIO4 name
Periodic acid
HIO3 name
Iodic acid
HIO2 name
Iodous acid
HIO name
Hypoiodous acid
H2SO3 name
Sulfurous acid
HNO3 name
Nitric acid
HNO2 name
Nitrous acid
H3PO4 name
Phosphoric acid
H3PO3
phosphorous acid
What is atomic mass?
The mass of an atom in atomic mass units (1 atom C = 12 amu)
What is average atomic mass?
Weighted average of all naturally occurring isotopes of the element (based on relative abundance)
To solve:
1) Convert percentage given of isotope into a decimal (60.0% -> 0.600)
2) Multiply decimal by amount of grams given of isotope
3) Add the atomic masses (products) together to find the average within the element
What is a mole?
A unit to count number of particles - contains as many elementary entities as there are atoms in exactly 12 grams of 12C
Avogadro’s number is used to find the number of ____ of a compound/element
atoms/particles
What is molar mass?
Mass of 1 mole of anything in grams
How do we convert from mass to atoms of an element?
Mass (g) –> Molar mass –> Moles –> Avogadro’s number–> Atoms
What is the molecular mass (molecular weight)?
Sum of the atomic masses (in amu) in a molecule
What is the formula mass?
Sum of atomic masses (in amu) in a formula unit of an ionic compound
What is the percent composition and how do we calculate it?
The amount of an element in a compound; calculated by:
1) Find the atomic mass of the element with respect to its coefficient in the equation
2) Divide atomic mass by the molar mass of the compound
3) Multiply the product by 100 to find the percentage
How would we find the empirical formula given the percent composition?
1) Convert the percent given into grams of an element (40.0% -> 40.0 grams of C)
2) Use the grams to find number of moles (by dividing by molar mass of compound)
3) Identify the smallest amount of moles and divide the other products by the smallest number to find a smallest compound ratio
4) If needed to achieve a whole number, multiply all the products by a common integer to achieve a whole number
5) Write out empirical formula with the subscripts :)
We cannot use the ____ to read a chemical reaction. Only moles and molecules
Mass (g)
Stoichiometric coefficients are consist with ____, not ____.
moles, grams
What is the limiting reagent?
The reactant used up first in the reaction
