Question

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Q5) Consider the combustion reaction between 13 ethane molecules and 42 oxygen molecules. Identify the limiting reactant. (Chapter 3)
A) water
B) ethane
C) none of the above
D )carbon dioxide
E) oxygen


Q7) Determine the molarity of a calcium hydroxide (molar mass: 74.10 g/mol) solution if 34.53 mL of the calcium hydroxide solution is required to neutralize 15.41 mL of a 2.456 M hydrochloric acid (molar mass: 36.46 g/mol) solution.
A)1.096 M
B)none of the above
C)5.480 × 10-4 M
D)0.5480 M
E)1.096 × 10-3 M


Q9) In which of the following orbitals does an electron in a rubidium atom experience the least effective nuclear charge?
A)2p
B)5s
C)7s
D)4d
E)3s


Q10) Using Lewis structures, determine the number of sigma (σ) and pi (π) bonds are there in a carbon dioxide molecule?
A) 1 σ and 2 π bonds
B) 2 σ and 2 π bonds
C) 3 σ bonds
D) 1 σ and 1 π bonds
E) none of the above


Q12) Using the Lewis structures for a carbon dioxide molecule and a carbonate ion, which of the following statements is true?
A) A carbonate ion has two different carbon-oxygen bond lengths, where one of the carbon-oxygen bonds is the same length as the carbon-oxygen bond in a carbon dioxide molecule.
B) A carbon dioxide molecule has two carbon-oxygen bond lengths, where one of the carbon-oxygen bonds is the same length as the carbon-oxygen bond in a carbonate ion.
C) none of the above predictions are true
D) All of carbon-oxygen bonds in a carbonate ion are shorter than the carbon-oxygen bonds in a carbon dioxide molecule.
E) All of the carbon-oxygen bonds in a carbonate ion are weaker than the carbon-oxygen bonds in a carbon dioxide molecule.

Q19) Calculate the number of grams of sodium hydroxide (molar mass: 40.00 g/mol) required to make 50.0 mL of a 0.200 M solution.
A) 0.400 g
B) 0.0100 g
C) none of the above
D) 4.00 x 102 g
E) 10.0 g

Answer 1

5) oxygen

7)0.5480 M

9)5s

10) 2 σ and 2 π bonds

12) All of the carbon-oxygen bonds in a carbonate ion are weaker than the carbon-oxygen bonds in a carbon dioxide molecule

19) 0.400 g

Step-by-step explanation:

For question 5

C2H6 + 7/2 O2 -----> 2CO2 + 3H2O

If 1 mole of ethane gives 2 moles of carbon dioxide

13 moles of ethane will give 13×2 = 26 moles of carbon dioxide

If 3.5 moles of oxygen gives 2 moles of carbon dioxide

42 moles of oxygen will give 42×2/3.5 = 24 moles of carbon dioxide

The reactant that gives the lower number of moles of product is the limiting reactant. This means that oxygen is the limiting reactant here.

7) concentration of acid CA =2.456 M

Concentration of base CB= ???

Volume of acid VA= 15.41 ml

Volume of base VB= 34.53 ml

Number of moles of acid NA= 2

Number of moles of base NB= 1

Ca(OH)2(aq) + 2HCl(aq) ----> CaCl2(aq) + 2H2O (l)

CB= CA VA NB/VB NA

CB= 2.456 × 15.41 ×1/34.53×2

CB= 0.548 M

9) For question 9, we have to look at the electronic configuration of Rb. We have [Kr]5s1. The outermost 5s1 level will have the least effective nuclear charge and is easily lost.

10) There are two sigma bonds and two pi bonds in CO2

12) The C-O bond length in the carbonate ion is 136 pm while the C-O bond length in CO2 is 116 pm. The longer the bond, the weaker the bond hence the C-O bonds in the carbonate ion are weaker than those in the carbon dioxide molecule.

19) From

m= mass of solute

M= molar mass of solute

C= concentration of solute

V= volume of solution

m/M = CV

m= MCV

m= 40.0gmol-1 × 50.0/1000 × 0.200

m= 0.4 g