Term
| Percent concentration of a solution is expressed as: |
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Definition
| Parts per 100 parts. Tip: percent is always "per 100" |
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Term
| What will one liter of one molar solution of any element or compound contain? |
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Definition
| A weight in grams equal to the Atomic Weight of that element. The key is one (1) mole of any element weighs (in grams!!) the atomic weight. |
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Term
| What "bonds" together in chemical bonding to form compounds? |
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Definition
| Atoms bond together to form molecules. These bonds can be between atoms of the same element like O2 or between different elements H2O |
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Term
| Two types of chemical bonds are ionic bonds and covalent bonds. describe each. |
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Definition
Covalent bonds are when two atoms share electrons.
Ionic bonds are where one atoms takes an electron from another atom making one positively charges and the other negatively charged, thus attracting one another to form a molecule. (example NaCl formed from a Alkali Metal and a Halogen) |
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Term
| The reaction 2C2H6 + 7O2 -- 4CO2 +6H2O has a ratio of 2 parts Ethane (C2H6) to 7 parts Oxygen (O2) How many parts of Ethane are needed to react with 21 parts of Oxygen? |
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Definition
| The first thing to recognize is that they have given you a "balanced" equation to describe the reaction. The left side has 4 carbons, 12 hydrogens, and 14 oxygens. The right side has the same number of atoms of each element. So...if the original balanced equation starts with 2 Ethanes to 7 Oxygens and the number of oxygens goes from 7 to 21 (an increase of 3X) then how many Ethanes are required to go along with 21 Oxygens? If 7 Oxygens becomes 21 Oxygens, then 2 Ethanes must become 6 ethanes (3X the original 2C2H6) to keep the equation balanced. Note: The quantities of the reactants will increase by 3X as well. |
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Term
| What is the concentration of 58.5 g of NaCl in 2 L of solution (the atomic weights are as follows: Na=23 g/mol Cl=35.5 g/mol |
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Definition
| You are given the atomic weights for the individual elements. For the molar weight of NaCl, just add the two together to get 58.5 which is the amount of Sodium Chloride that the problem stated is in two liters of solution. If it was only one liter of solution than the concentration would be 1 mol (per definition of molar solution concentrations). In this case we have twice as much solution (2 liters) and only one mole of NaCl atoms so it's concentration is half (two liters vs one). So... the answer is 0.5 mol NaCl |
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Term
| What is the strongest type of chemical bond? |
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Definition
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Term
| Which is stronger: Bonds or intermolecular forces? Also - name the two types of bonds and three types of intermolecular forces. |
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Definition
Bonds (Covalent and Ionic) are stronger than the weaker intermolecular forces.
Intermolecular Forces:
- Hydrogen Bonds
- Dipole-Dipole
- Dispersion forces (weakest) |
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Term
| What are the five types of chemical reactions? |
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Definition
- Synthesis: reactant1 + reactant2 - product
- Combustion: A compound (almost always one with Carbon) reacts with Oxygen and heat to form CO2 and H20
Decomposition: A single compound breaks down into to products.
- Single replacement: A "two element" compound reacts with a single element resulting in a different "two element" compound and a single element
- Double replacement: Two "two element" compounds react to create two different "two element' compounds |
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Term
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Definition
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Term
What is Oxidation?
What is Reduction? |
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Definition
Oxidation: losing electrons
Reduction: gaining electrons
OIL-RIG Oxidation is losing, reduction is gaining |
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Term
| What is the oxidation state (or charge) on Oxygen in a compound? |
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Definition
-2
remember O2 by itself has a charge of zero |
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Term
| What is the oxidation state (or charge) on Hydrogen in a compound? |
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Definition
+1
remember H2 by itself has a charge of zero |
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Term
| What is the oxidation number (charge) on Carbon in 2C2H6 ? |
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Definition
| The total charge on the compound is always zero. Since each H in a compound has an oxidation number (charge) of +1, then the H6 has an oxidation number if +6. Therefore the Carbon must offset this +6. Note: Ignore the "2" in front of the Carbon. However you must consider the fact that it is C2. C2 must have an oxidation number of -3 to offset the +6 on Hydrogen to get to "zero" on the whole compound. (-3 x 2 = -6) |
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Term
A solution with a pH below 7 is a?
A solution with a pH above 7 is a ?
A solution with a pH = 7 is a? |
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Definition
pH < 7 is an acid
pH > 7 is a base
pH = 7 is neutral |
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Term
| What are the two things in an acidic or basic solution that determine the acidity/alkalinity? |
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Definition
H+ Hydrogen ions (cations)
OH- Hydroxide groups (anions) |
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Term
| When a solution has a pH of 7.0 - what is the ratio of H+ ions to OH- ions |
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Definition
For a neutral pH of 7.0 there are an equal number of H+ and OH- ions. So... the ration is 1:1
This is the defination of the midpoint (7.0) of the pH scale. |
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Term
Write the formula for water (H2O) dissociating into H+ and OH- |
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Definition
H2O -- H3O + OH-
or
H2O -- H+ + OH-
Note: The acid part of this disassociation is usually written as H+ but it's the same thing as H3O (Hydronium)
The third H is really the H+ ion holding onto H2O |
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Term
| What happens when an acidic compound like Hydrochloric acid (HCl) is added to an aqueous solution? |
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Definition
| There is an increase in H+ ions and the solution becomes more acidic (pH drops) |
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Term
| What happens when a compound that is basic (a base) is added to an aqueous solution? |
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Definition
| The number of OH- ionsd increase and the solution becomes more basic (pH increases) |
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Term
| A solution with a pH of 4.5 would be a ____? |
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Definition
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Term
| A solution with a pH of 8 would be a ____? |
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Definition
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Term
| What element has no neutron and often loses an electron? |
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Definition
| Hydrogen (H) has a proton and no neutron. It readily loses its one electron and when this happens, Hydrogen becomes a bare single proton. For this reason, acids which create H+ ions are considered to be protons donors |
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