Hydrosphere Midterm Review Guide
Identify the following as ionic compounds or covalent compound CH4
Covalent
Identify the following as ionic compounds or covalent compound H2O
Covalent
Identify the following as ionic compounds or covalent compound NH3
Covalent
Identify the following as ionic compounds or covalent compound O2
Covalent
Identify the following as ionic compounds or covalent compound SO2
Covalent
Which type of bond is within a water molecule (intra-molecular force)
Covalent bond between H and O
What is the Reaction Type: ___ 2 Fe(OH)3 → 1 Fe2O3 + 3 H2O
Decomposition
Explain how electrons are shared between atoms in a polar covalent bond and in a nonpolar covalent bond.
Nonpolar - shared evenly Polar - shared unevenly
What is the Reaction Type: 1 Fe2O3 + 3 C → 3 CO + 2 Fe
Single Replacement
Define sensible heat and give examples of sensible heat as energy is absorbed by water.
Define sensible heat and give examples of sensible heat as energy is absorbed by water.
What is the Reaction Type: 3 BaCl2 + 1 Al2S3 → 3 BaS + 2 AlCl3
Double Replacement
High Specific Heat
-Water absorbs a lot of energy before it changes temperature.
In an ENDOthermic reaction, energy is _________________ and should be included on the _________________ side of the reaction.
ABSORBED, REACTANTS
Write the chemical formula for Dicarbon hexahydride
C2H6
Write the chemical formula for Carbon dioxide
CO2
What is the Reaction Type: 2 C2H6 + 7 O2 → 4 CO2 + 6 H2O
Combustion
What scientific law provides the rationale for why chemical equations must be balanced?
Conservation of mass
Write the chemical formula for Dihydrogen monoxide
H2O
Which type of bond is between water molecules (inter-molecular force)
Hydrogen bonds (weak attractions)
Explain the difference between what the valence electrons do in an ionic bond and what they do in a covalent bond.
In an ionic bond (between a metal and a nonmetal) the metal gives electrons to the nonmetal. Electrons are transferred. In a covalent bond (between 2 or more nonmetals) electrons are shared between the atoms.
Explain why the heat of vaporization (ΔHovap) of water is so much greater than the heat of fusion (ΔHofus) of water.
In order to vaporize (boil) water, the water molecules must have enough energy to completely separate from one another. Since water forms hydrogen bonds, those bonds must be broken to separate the molecules which requires a lot of energy. The heat of fusion is the heat required to melt ice to form water which requires much less energy since hydrogen bonds do not need to be broken.
Identify the following as ionic compounds or covalent compound MgCl2
Ionic
Using the periodic table, how can you tell whether a bond is ionic or covalent? What type of elements make up covalent compounds? Ionic? What type of element is included in both?
Ionic - between a metal and a nonmetal Covalent - between two or more nonmetals
When drawing the Lewis structure of a molecule, how do you know which atom is the central atom?
It is the element with the most unpaired electrons. It is often the first element in a covalent formula.
Define latent heat and give examples of latent heat as energy is absorbed by water.
Latent heat refers to the heat energy absorbed during a phase change that does NOT cause the temperature of the substance to change. The energy is either going into breaking the crystal structure of water (latent heat of fusion) or breaking hydrogen bonds (latent heat of vaporization).
What types of substances are soluble in water? (ionic, non-polar covalent, polar covalent
Like dissolves like so...polar water dissolves polar substances and ionic substances
Write the chemical formula for Trinitrogen pentoxide
N3O5
What is the c (specific heat) of water? _________J/g०C How many grams of water are in a container if the addition of 186 J of energy raises the temperature of the water by 12oC? (show all 4 steps)
Q = 186 J c = 4.186 ΔT= 12 QcΔT=m 3.70 g
By how much does the temperature change when 175 J of energy is absorbed by 7.25 g of water?
Q=175 J m=7.25 g c=4.186 Qmc= ΔT 5.8 C
Write the specific heat equation, label what each variable represents AND the units that are used to measure it.
Q=cmΔT Q= heat added C= specific heat M= mass ΔT= change in temperature
In an EXOthermic reaction, energy is _________________ and should be included in the balanced chemical equation on the _______________ side of the reaction.
Released, Products
Write the name for the following covalent compound SeBr5
Selenium pentabromide
What is the Reaction Type: 4 Si + 1 S8 → 2 Si2S4
Synthesis
In the calorimeter lab, the amount of energy in one gram of candle wax that we calculated was significantly lower than the actual amount of energy stored in 1g of wax.... Explain why
The calorimeter we used allowed a lot of energy to escape to the surrounding environment.
What are valence electrons? Explain their importance in chemical bonding.
The electrons in the outermost shell of the atom. They are important because they participate in chemical bonding between atoms. Atoms gain, lose or share valence electrons to achieve a full octet.
Describe, identify, and balance and calculate energy transfer for different types of chemical reactions.Give two examples of why the high specific heat of water is beneficial (for the planet, the body, etc.):
The oceans regulate the temperature of the planet. Organisms are mostly water so the water regulates the temperature of living things. Water can be used to cool many things including industrial processes and the engine of your car.
Define electronegativity and describe which area of the periodic table has the highest electronegativity.
The tendency of an element to attract bonding valence electrons. The upper right corner (F ) has the highest electronegativity. Most metals have a lower electronegativity and most nonmetals have a higher electronegativity.
Universal solvent
Water dissolves many substances (polar and some ionic). Salt and sugar dissolve in water.
Surface Tension
Water forms a film on its surface due to cohesion. Paperclips "float" on water, bugs walk on water.
Cohesion
Water sticks to itself. Water forms a droplet, surface tension
Adhesion
Water sticks to other surfaces. Water forms drops on a window or plant leaves
Write the name for the following covalent compound N2O3
dinitrogen trioxide
Write the name for the following covalent compound P2O4
diphosphorus tetraoxide
Write the name for the following covalent compound FCl
fluorine monochloride
A 25g object is heated from 3oC to 17.5oC and measures a heat increase of 45.7 J. Is this object Bismuth, Gold, or Lead? (specific heat for bismuth = 0.123 J/goC, gold = 0.126 J/goC, lead = 0.128 J/goC)
m=25g ΔT=14.5 Q=45.7 J QmΔT=c c=.126 so the material is gold
Write the name for the following covalent compound SiF6
silicon hexafluoride
Explain WHY water is a polar molecule:
since oxygen is more electronegative than hydrogen, the shared electrons in the covalent bonds are pulled more toward the oxygen giving the oxygen side of the molecule a partial negative charge and the hydrogen side a partial positive charge
Write the name for the following covalent compound SCl2
sulfur dichloride
Write the name for the following covalent compound SF7
sulfur heptafluoride
Scenario: A 25 gram sample of copper and a 25 gram sample of water (both at room temperature) are placed in a refrigerator for 10 minutes. Which substance will be colder after 10 minutes Compare the amount of energy the objects "lost" while in the fridge. When removed from the fridge, which substance will warm up faster?
the copper since metals have a low specific heat They lost the same amount of energy the copper
Write the name for the following covalent compound P3Se6
triphosphorous hexaselenide
