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BASIC REVIEW CH.1-8

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Answer Explanations Coming Soon!

 

Question 1

How many protons does copper have?

Periodic Table and protons

 

Explanation

 

Question 2

How many electrons does copper have? Remember atoms are neutral.

 

 

Question 3

How many neutrons does copper-63 have? Help given in feedback.

 

Explanation

Remember the protons and neutrons constitute most of the mass of an atom. For example, iron-56 has an approximate mass of 56 g per mol. Per atom, there are 26 protons and 56-26 = 30 neutrons.

 

Question 4

What is the mass of 1 mol of CO2 in g?
Correct

 

Explanation

Molar Mass of CO2 = 44 g

1 mol of CO2 =  x g / 44 (g/ mol)

 

Question 5

What is the mass of 39 molecules of SO3 in g?

Using Avagadro's Number

Correct

 

Explanation

39 molecules / (6.022*10^23)  * 80.066 = 5.18e-21

(molecules/ Avogadro's #) * MolarMass(g)


 

Question 6

Correctly match the element with the property.
Metal that reacts with cold water to produce OH- and H2(g) Correct
Metal (all conduct electricity)--no reaction with water, but reacts with acid to produce H2 gas Correct
Non-metal--does not conduct electricity Correct
Noble gas--inert, stable electron configuration Correct
Semimetal--poor conductor of electricity Correct

 

        

 

Question 7

What is the correct formula for aluminum sulfide?
Select one:
 Correct

 

Explanation

Al 3+;  S2-

Al2S3

 

Question 8

Which compound is the most ionic?

Select one:
 Correct

 

Explanation

Ionic compounds-

 

Question 9

Match properties correctly

Quantum Numbers

Indicates energy and size of orbital Correct
l=0 Correct
l=1 Correct
l=2 Correct
l=3 Correct
Number of possible electron spins for each orbital Correct

 

Explanation

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Question 10

Select the correct set of quantum mechanical numbers for an electron in an s, p, d, and f orbital. (4 correct answers.)

Allowed Combination of Quantum Numbers

Select one or more:
 Correct
 Correct
 Correct
 Correct

 

Explanation

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Question 11

Correctly match the information for the angular momentum quantum number (l) which gives the shape of the orbital. A nodal plane is a region where the electron density is zero, that is, the probability of finding the electron there is zero.

The maximum number of electrons in an electron orbital. Correct
Spherically symmetric orbital--no nodal planes Correct
Orbital shaped like a peanut or dumbbell--one nodal plane Correct
4 of the 5 orbital shaped like a double peanut--2 nodal planes Correct
Orbital shaped like flower or fancy--3 nodal planes Correct

 

Explanation

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Question 12

What is the ground-state electron configuration for S?

Electron Configurations

Select one:
 Correct

 

Explanation

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Question 13

What is the electron configuration for S2-?
Select one:
 Correct

 

Explanation

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Question 14

What is the electron configuration for K1+?
Select one:
 Correct

 

Explanation

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Question 15

Match atomic radius from largest to smallest.

Atomic Radius

K Correct
Al Correct
Na Correct
Ar Correct
S Correct

 

Explanation

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Question 16

Match ionization energies from smallest to largest.

Ionization Energy

K Correct
Al Correct
Na Correct
Ar Correct
S Correct

 

Explanation

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Question 17

What is the correct formula for iron (III) oxide? 
Select one:
 Correct

 

Explanation

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Question 18

Which of the following tin (IV) compounds makes sense using oxidation states and conservation of charge?

Oxidation State and Polyatomic Ions

Select one:
 Correct

 

Explanation

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Question 19

Warmup question. How many moles of Ca(OH)2 are required to neutralize (react completely with) 0.89 moles of HCl? The balanced reaction is:

2HCl(aq) + Ca(OH)2(aq) → 2H2O(l) + CaCl2(aq)

Using Balanced Equations

Correct

 

Explanation

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Question 20

What volume in L of 0.35 M Ca(OH)2 is required neutralize 0.39 moles of HCl? The balanced reaction is:

2HCl(aq) + Ca(OH)2(aq) → 2H2O(l) + CaCl2(aq)

Using Balanced Equations II

Correct

 

Explanation

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Question 21

What volume in L of chlorine at 30oC and 611 torr is required to react completely with 3.72 g aluminum:

2Al(s) + 3Cl2(g) → 2AlCl3(s) 

Calculate the moles chlorine needed (as in the previous problem), then use the ideal gas law--PV = nRT. Additional help is given in the feedback.
Correct

 

Explanation

Procedure: g Al --> mol Al --> mol Cl2. Next solve for V in PV = nRT. Did you remember to convert torr to atm and oC to K?

 

Question 22

The following reaction takes place at a certain elevated temperature:

Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(s) 

What is the percent yield of iron if 41.1 g Fe2O3 in excess CO produces 25.0 g Fe? The M.W. of Fe2O3 is 159.7 g/mol and the M.W. of CO is 28.01 g/mol. 

Recall that the percent yield is the actual yield divided by the theoretical yield times 100%. Additional help is given in the feedback.

Correct

 

Explanation

Procedure: g Fe2O3 --> mol Fe2O3 --> mol Fe --> g Fe (This is the theoretical yield. Note M.W. CO is not used.) Take actual yield, 25.0, and divide by the theoretical yield and then multiply by 100 (to change to percent yield).

 

Question 23

What is the mass percent of carbon in sugar, C12H22O11? M.W. sugar = 342 g/mol. 

Help is given in the feedback.

Correct

 

Explanation

Mass percent C = (mass C/ total mass) x 100%. Pick 1 mol sugar. What is the mass? How many mol C in 1 mol sugar? What is the mass C?

 

Question 24

Analysis of 3.500 g sample of an unknown compound shows that it contains 1.400 g C, 0.235 g H, and the rest O. What is the empirical formula of this compound? 

Hint, given in feedback.

Select one:
 Correct

 

Explanation

Because total mass is conserved, the mass of O can be found. Convert each mass to moles. Convert moles to smallest whole numbers. Sometimes it is sufficient to divide each by the smallest number of moles. Compare the number of moles of each element in the compound.

 

Question 25

Hemoglobin has a mass of about 67,000 g/mol. It is 0.3335% iron by mass. How many iron atoms are in a molecule of hemoglobin? 

Help is given in the feedback.
Correct

 

Explanation

Find mass of iron in 1 mole of hemoglobin. Divide by M.W. of iron. This gives moles of iron in 1 mole of hemoglobin. It equals the atoms of iron in 1 molecule of hemoglobin.


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