UNIT 3 PSYCH HW - Cumualitve
What is the charge of iron (Fe) in the compound Fe2O3?
+3
What would be the charge of bromine, Br, in order to satisfy the octet rule? Hint: Look at the column number.
-1
By now you've noticed that the cards represent charged ions. If you want to combine these ions to make a stable material, what does the total charge need to be on the final product?
0
Ca___Cl___ How many calcium atoms?
1
How many electrons does Cl want to gain? Hint: How many are gained to form a stable noble gas electron configuration, ns2np6 (octet rule)?
1
How many electrons would potassium, K, need to get rid of to satisfy the octet rule? Hint: You will want to refer to the energy well diagram you were asked to draw.
1
The Second Law of Thermodynamics (Law of Increasing Disorder) places limits on the efficiency of energy conversion. Which of the following is allowed?
100% conversion of electricity to ambient temperature thermal energy
Each molecule of methane has the formula CH4. If there are 4,000 carbon atoms present, how many hydrogen atoms will be required to convert all the carbon atoms into methane?
16,000
Given the electron configuration diagram, predict how many electrons Mg would be expected to lose in ionic compounds. Hint: How many are lost to form a stable noble gas electron configuration, ns2np6 (octet rule)?
2
How many electrons would sulfur need to gain to satisfy the octet rule?
2
How many more electrons does unbound oxygen need to fill its 2nd shell? (You may find it helpful to draw the energy well on scratch paper.)
2
How many nonmetal atoms (bromine) are needed to take all the electrons that the metal atoms (calcium) want to give?
2
Na___O___ How many sodium atoms?
2
What would be the charge of calcium, Ca, in order to satisfy the octet rule? Hint: Look at the column number.
2
Now ask yourself how many potassium (metal) atoms are needed to give all the electrons that one sulfur (nonmetal) atom wants to take.
2 potassium atoms per sulfur atom
Each molecule of nitric acid has the formula HNO3. If there are 6000 oxygen atoms present and 6000 nitrogen atoms present, how many hydrogen atoms will be required to convert all of the oxygen atoms into nitric acid?
2000
Which of the following is a correct and balanced equation showing the reaction of calcium and oxygen? (While several of the equations may be balanced, only one has the correct products and reactants as well as being correctly balanced.)
2Ca + O2 = 2CaO
In which of the following processes is the end product more ordered than the reactants? (In which process does entropy decrease in the system?)
2H2 (gas) + O2 (gas) = 2 H2O (gas)
Na___N___ How many sodium atoms?
3
How many bonds does each carbon have in propanal?
4
Where do you think the location of the highest peak would be for butanal (or butyraldehyde), the next member of the aldehyde family after propanal?
72
which of the following is a correct comparison of metals and semi-conductors?
A metal's resistance increases when temperature increases while a semi-conductor's resistance decreases.
If GaAs forms a semiconductor like Ge, which of the following elements will form a semiconductor like Si? (Hint: Look at the periodic table.)
Al and P
Which of the following is not why alloys are useful to us today?
Alloys have a higher conductivity rate.
Why is cookware (pots and pans) most often made of metal?
Because it is easy to shape into a pan Because it has a high melting point Because it is a good conductor of heat and electricity
Why are metals opaque?
Because metals have empty, overlapping orbitals for their electrons that create very closely spaced energy levels.
Why is overheating such a problem for electronics?
Because the hotter a semi-conductor becomes, the better it conducts electricity.
Which of the following best explains why metals are opaque and shiny?
Because there are so many empty orbitals that the electrons can absorb and emit any frequency of light.
What is the chemical formula for acetaldehyde?
C2H4O
What is the chemical formula for this member of the family that you drew?
C4H8O
The chemical formula of the next family member after butylene will have what chemical formula?
CH2CHCH2CH2CH3 (also written C5H10)
What would be the chemical formula of the ionic compound between calcium and bromine?
CaBr2
Sort the cards into three piles by card size. What are the common characteristics of the cards in each pile?
Card size means they all have the same size charge.
What happens to the entropy of the universe as the products are formed?
Chemical potential energy is converted into thermal energy resulting in an increase in entropy.
The "cards" are separated top to bottom by color. What are the common characteristics of the cards of each color? (pick all right answers)
Color indicates the ions all have the same sign (positive or negative) charge. Color indicates whether they're metals or non-metals. Color indicates whether they gave away or stole electrons.
On paper, draw a ball-and-stick diagram for the next family member in the aldehyde family after propanal. Which of the following diagrams best represents this next member of the aldehyde family?
D
Which appears more chaotic, the gas with the higher temperature or the lower temperature? If you change the temperature or type of gas, be sure to click on the start button to restart with your new settings.
Disorder is greater when the temperature is higher.
A car can't convert all the energy from its fuel to macroscopic kinetic energy. Why?
Entropy would decrease.
Because it is possible to separate the atoms back into different areas, the process is reversible.
False
It is impossible to do work and sort the molecules into separate areas.
False
If the two figures represent snapshots in time of an irreversible process, which figure came first and why?
Figure 18.2 because molecules rush inside the box to get rid of the vacuum Think of putting these two pictures in a timeline like a movie. Which makes sense to view: the gas molecules rushing out of the box to form a vacuum or the gas molecules rushing into the empty box to fill it?
What is the chemical formula for the most common fragment of acetic acid?
H3C2O
What is the chemical formula for the most common fragment of formic acid?
HCO, , the "OH" knocked off.
What happens to the number of molecular orbitals as the number of atoms that come together increases?
The number of molecular orbitals increases.
A perfume bottle drops and shatters on the floor of a room. (An irreversible process has just occurred—the breaking of the bottle!) You observe that you can smell the perfume throughout the entire room a few seconds later. Which of the following explanations of this observation is correct?
The perfume's odor is caused by its molecules. Molecules of perfume in the liquid are in random motion. When the bottle breaks, the molecules can vaporize and spread throughout the room, mixing with the air in the room. The room with perfume molecules spread around it is more disordered than perfume molecules concentrated in a spot surrounding the broken bottle.
A refrigerator is a small box of cold atoms in a warmer room. Since this is more ordered than having all of the atoms mixed, how is this possible?
The refrigerator has to turn enough ordered electrical potential energy into disordered thermal energy that the increased disorder in the energy more than makes up for the increased order from cooling down the inside of the refrigerator.
Suppose you decide to use the refrigerator to cool down the apartment by leaving the door open. What happens to the temperature of the kitchen over the next few hours? Why?
The room will heat up. Because the heat absorbed on the inside of the open fridge is smaller than the energy the refrigerator releases into the room.
What is more ordered, a warm room that contains a separate box full of low energy atoms. Or a room where all of the atoms are mixed together?
The room with the separate box of atoms.
A window air conditioner is normally placed in a window so the hot air from the back blows outside. What would happen if the air conditioner were placed in the middle of a closed room and turned on?
The room would heat up because all of the energy absorbed by the air conditioner, both thermal and electrical potential, is released back into the room as thermal energry
Which of the following processes is closest to an ideal reversible process?
an ice cube floating in a glass of water at zero degrees
When does the system have more order?
before the separator is removed Try playing the video in reverse in your head—does it make sense for the molecules to go from mixed to separate? Systems tend to move from order to disorder unless energy is applied to create order.
What happens to the energy of the system as this compound is formed?
energy decreased
Metals have higher ionization energies than nonmetals do.
false
True or false: Current can flow in all directions in an LED.
false
C3H8 (gas) + 5O2 (gas)⇒ 3CO2 (gas) + 4H2O (vapor), energy given off:
favorable energy and entropy change
C6H12O6 (solid) + 3O2 (gas) ⇒ 3CO2 (gas) + 6H2O (vapor), energy given off:
favorable energy and entropy change
Characterize the following reactions as occurring with a favorable energy change when the reactants become the products, a favorable entropy change when the reactants become the products, or both. Remember, gases have more disorder than liquids, which have more disorder than solids. 2H2 (gas) + O2 (gas) ⇒ 2H2O (gas), energy is given off:
favorable energy change Thermal energy is released. This means the products have a lower overall energy than the reactants, which is favorable.
NH4NO3 (solid) + H2O (liquid) ⇒ NH4+ + NO3- in water solution, energy absorbed:
favorable entropy
In acetaldehyde, how many of each type of bond are there?
five single, one double, zero triple
Which type of energy is the most ordered?
gravitational potential energy
Pure aluminum metal has a melting temperature of 660˚C. The process of liquid aluminum freezing to solid aluminum at this temperature is ________.
irreversible This situation is very similar to the ice melting and refreezing at 0°. However, rather than just sitting at that temperature with the amounts of solid and liquid constant, the aluminum is changing phase. Because it is going from one state to another, heat has to be transferred from the aluminum to the surroundings, and the entropy of the universe is increasing as a result. The aluminum is getting more ordered as a solid, but the heat transferred to the rest of the universe increases its disorder in a way that more than makes up for neatly stacking the atoms in a solid.
In an irreversible process, what happens to the overall disorder of the universe?
it increases
Suppose it's hot outside and your air conditioning is broken. When you first open the door of the refrigerator, you get hit with a pleasant blast of cold air. What is happening to the disorder of the universe in those first few seconds?
it increases
Which type of atom has valence electron states high enough in energy that they overlap with the stacked-together molecular orbitals that form the conduction band?
metal
Which type of atom has valence electrons higher in the energy well?
metal
Which of the following is atomic matter rather than molecular or network matter?
neon gas
What classification of matter is magnesium chloride?
network matter
Are the hydrogen atoms still balanced? H2 + O2 → 2H2O
no
Consider a refrigerator and its contents to be the system. Warm food is cooled to a lower temperature. Warm water is cooled in the freezer and eventually frozen to ice. Do these two processes, cooling food and freezing water, increase the entropy inside the refrigerator?
no
If you were to put your hand behind the back of an operating refrigerator, would you feel cold air coming out of the exhaust?
no
The unbalanced equation is as shown: H2 + O2 → H2O Are the oxygen atoms balanced?
no
The unbalanced equation is as shown: H2 + O2 → H2O Could you balance the oxygen atoms by changing H2O to H2O2?
no
Which type of atom has the highest ionization energy?
nonmetal
Which of the following is not a compound?
oxygen molecule (O2)
When you compare the band gap for a red and a blue LED, what is true?
red LED has the smallest band gap
Locate the elements palladium (Pd, atomic #46) and nickel (Ni, atomic #28) on the periodic tableLinks to an external site.. If Pd is combined with Ni, which of the following characteristics will the product show at room temperature?
shiny, malleable solid
A material that is made up of one type of molecule, where each molecule is made of 2 different types of atoms is still a pure substance.
true
Are oxygen atoms balanced if a 2 is placed in front of water to make the following equation? H2 + O2 → 2H2O
yes
Hydrogen (H2) and oxygen (O2) react to produce water (H2O). The unbalanced equation is as shown: H2 + O2 → H2O Are the hydrogen atoms balanced?
yes
If the entropy associated with the contents of the refrigerator decreases, would the entropy of the surroundings need to increase in order for the law of increasing disorder to be obeyed?
yes
Instead of cold air coming from the operation of the exhaust of the refirgerator, you would feel hot air. The hot air increases the temperature of the surroundings. Is this a process that increases the entropy of the kitchen?
yes
Is the equation balanced now? 2H2 + O2 → 2H2O
yes
We see a large amount of order in the world around us, from life to currents in the air and ocean. How is this consistent with the law of increasing disorder?
It is because the sun provides additional high-order energy to the world to create this order.
Which of the following correctly applies the law of increasing disorder to an air conditioner?
It is true that the heat flow from the cold region to the hotter region increases order, but this is made up for by increasing the disorder of energy from another source.
How does a catalyst affect a reaction?
It lowers the activation energy.
What would be the chemical formula of the ionic compound between potassium and sulfur? Hint: When writing the formula, the metal always comes first.
K2S
Magnesium chloride forms a solid in which two chloride ions are found for every magnesium ion, but no discrete molecules are observed in the solid. What is the simplest formula for this compound?
MgCl2
Can sulfur be considered a compound? Why?
No, it is composed of only one type of atom.
What is the chemical formula for sulfur?
S8
The gasoline engine of an automobile is considerably less than 100% efficient. This means that not all of the energy in the gasoline is turned into kinetic energy of the car. Which of the following best explains why?
Some of the chemical potential energy in the gasoline must become ambient thermal energy if the rest is to supply the kinetic energy of the automobile. This means some energy must be wasted.
What happens to the overall entropy in the universe as this compound is formed?
The entropy increases.
What happens to the valence electrons as the product (MgO) is formed?
The magnesium atoms' valence electrons are effectively transferred to oxygen.
What is more ordered, a box of red legos containing a separate box of blue legos or the same two boxes each containing a mix of the red and blue legos?
The separated boxes have more order.
What happens to the spacing between the energy of one molecular orbital and the next one immediately above or below it as the number of atoms that come together increases?
The spacing between energy levels decreases.
If you compare metals with ionic compounds, what do they have in common?
Their melting temperatures are similar
What is the likelihood that the gases would gain the order they had if we left the system alone for a long time?
There is virtually no chance the gases would spontaneously unmix. The mixed system has more entropy (disorder). Because it has more entropy, it is more likely to occur. It is very unlikely to unmix without any outside assistance.
Which of the following would best describe the room temperature characteristics of the substance that results from the reaction between magnesium (Mg) and oxygen (O)?
a brittle, transparent, electrically non-conducting solid
What is the formula for ethene?
c2h4
What would be the name of this ionic compound?
calcium bromide
In order for an energetically favorable chemical reaction to occur
chemical potential energy must decrease as a result of the reaction.
