Friday
April 18, 2014

Homework Help: chemistry

Posted by Anonymous on Sunday, July 3, 2011 at 6:37pm.

Which of the following pairs of molecules have the same oxidation number for carbon?

CO and CO2
CH4 and CCl4
C6H12O6 and C(s)
H2CO and COCl2
Carbon always has an oxidation number of +4

What mass of CuSO4.5H2O would you need to prepare 250.0 mL of a 0.250 M solution? [MW of CuSO4.5H2O = 249.5 g/mol]

2.5 g
15.6 g
25.0 g
62.5 g
15600 g

Calculate the concentration of a solution formed when 15.0 mL of 6.00 M HCl are diluted with 25.0 mL of water.

0.150 M
0.240 M
2.25 M
3.60 M
6.00 M

Calculate the molarity of a sodium hydroxide solution if 10.42 mL of this solution are needed to neutralize 25.00 mL of 0.2043 M oxalic acid.

H2C2O4(aq) + 2NaOH(aq) --> Na2C2O4(aq) + 2H2O(l)

1.500 M
0.9803 M
0.4902 M
0.2500 M
0.1042 M

What is the oxidation number of Cr in potassium dichromate, K2Cr2O7?

+2
+4
+6
-4
-6

What is the molarity of a solution made by having 90.0 g of acetic acid, CH3CO2H, in 0.750 L of solution and given the atomic weights: C = 12.01 amu; H = 1.008 amu; O = 16.00 amu?

0.076 M
1.12 M
5.20 M
0.90 M
2.00 M

How many grams of CaO are required for complete reaction with the HCl in 275 mL of a 0.523 M HCl solution? The equation for the reaction is,

CaO + 2HCl --> CaCl2 + H2O
and the atomic weights are Ca = 40.08 amu; O = 16.00 amu.


806 g
403 g
8.06 g
4.03 g
0.523 g

What is the concentration of a NaOH solution made by dissolving 10.0 g NaOH in 50.0 mL of water and adjusting the volume to 250.0 mL?

1.00 x 10-3 M
1.00 M
5.00 M
16.0 M
40.0 M

For the redox reaction:

Ca(s) + 2H2O(l) --> Ca2+(aq) + 2OH-(aq) + H2(g)
which of the following statements is true?


Ca is the oxidizing agent.
H2 is reduced.
Ca is reduced.
H2O is the oxidizing agent.
H2O is oxidized.

Sodium thiosulfate is used with silver bromide in film developing. The formula for sodium thiosulfate is Na2S2O3. What is the oxidation number for S, sulfur?

-2
+2
-4
+4
+6

Calculate the molarity of vinegar (acetic acid) solution if you need 34.57 mL vinegar to neutralize (use up) 25.19 mL of 0.1025 M NaOH.

CH3COOH(aq) + NaOH(aq) --> CH3COO-(aq) + Na+(aq) + H2O

0.07469 M
0.07287 M
0.03457 M
0.02519 M
0.1025 M

Students were trying to determine the identity of a substance dissolved in water. The solution was odorless and colorless. After they had narrowed the list of possible substances to five compounds they added solutions of Na2S, KOH, and HCl to individual samples of the unknown and recorded the results as shown in the table.

Possibilities: AgNO3 ; Na2CO3 ; Na2S ; NaCl ; NH3

Table 1: Observations of Unknown with Test Reagents

with Na2S with KOH(aq) with HCl(aq)
unknown colorless solution;
no precipitate;
no bubbling colorless solution;
no precipitate;
no bubbling colorless solution;
no precipitate;
no bubbling

The dissolved "unknown" substance in the solution is:


AgNO3
Na2CO3
Na2S
NaCl
NH3

Students were trying to determine the identity of a substance dissolved in water. The solution was odorless and colorless. After they had narrowed the list of possible substances to five compounds [AgNO3, NaCl, HCl, Na2CO3, BaCl2] they added solutions of AgNO3, NaCl and Na2S to separate samples of the unknown and recorded the results as shown in Table I:

Table I: Observations of Unknown with Test Reagents

with AgNO3(aq) with NaCl(aq) with Na2S(aq)
unknown colorless solution;
no precipitate;
no bubbling white precipitate;
no bubbling black precipitate;
no bubbling

The substance dissolved in the "unknown" solution is:


AgNO3
NaCl
HCl
Na2CO3
BaCl2

Oxalic acid, H2C2O4, reacts with the chromate ion in acidic solution as follows:

3H2C2O4(aq) + 2CrO42-(aq) + 10H+(aq) --> 6CO2(g) + 2Cr3+(aq) + 8H2O(l)
What is the molarity of the oxalic acid solution if 10.0 mL of this solution consumes 50.0 mL of 0.0350 M CrO42-?


0.263 M
0.175 M
0.00700 M
0.0350 M
0.0105 M

You carried out an acid-base titration. You obtained 2.50 x 102 mL of 0.107 M HCl. This required 17.00 mL of KOH solution for exact neutralization. What is the molarity of the KOH solution?

0.107 M
0.168 M
1.57 M
2.50 M
2.65 M

What volume of 0.500 M glucose, C6H12O6, contains 3.01 x 1022 molecules of glucose?

5.00 x 101 mL
1.00 x 102 mL
5.00 x 102 mL
1.00 x 103 mL
none of these

What is the molarity of chloride ion in 0.123 M solution of BaCl2?

0.0615 M
0.123 M
0.246 M
1.369 M
1.23 M

You have a job in the General Chemistry Prep Laboratory. Your first task is to prepare five 1000-mL volumetric flasks, each containing 1.000 L of 0.100 M HCl. You will do this by adding a measured volume of concentrated HCl, which is 11.6 M and making up the rest of the volume by filling the flasks with H2O up to the mark. The volume of concentrated HCl you will add to each flask is:

0.862 mL
8.62 mL
86.2 mL
1.16 mL
11.6 mL

An experiment calls for 200 mL of 2.0 M HCl. If you had a 9.0 M stock solution of HCl on hand, how many mL of this solution would be required?

400 mL
125 mL
44 mL
14 mL
9.0 mL

All of the following are soluble compounds, EXCEPT:

(NH4)2CO3
K3PO4
Sr(OH)2
CsNO3
Mg(OH)2

Which of the following does not form a strong electrolyte?

Ba(OH)2
H2SO4
NH3
NaCl
Sr(NO3)2

The following titration reaction was carried out:

2HCl + Ba(OH)2 --> BaCl2 + 2H2O
If 22.0 mL of 2.5 M HCl was used to neutralize 50.0 mL of a Ba(OH)2 solution, what was the concentration of the base?


2.2 M
1.5 M
1.1 M
0.85 M
0.55 M

Which of the species in the following complete ionic equation are spectator ions?

2KCl(aq) + Pb(NO3)2(aq) --> PbCl2(s) + 2KNO3(aq)

K+, Pb2+
Pb2+, Cl-
NO3-
Cl-, NO3-
K+, NO3-

How many electrons are being transferred in the following redox reaction?

Cu(s) + ZnCl2(aq) --> Zn(s) + CuCl2(aq)

1
2
3
4
it cannot be determined

Using the Activity Series below, which of the following redox reactions will NOT react to form product?

Al(s) + NiCl2(aq) -->
Mn(s) + HBr(aq) -->
Ag(s) + AuCl3(aq) -->
PtBr2(aq) + H2(g) -->
Hg(l) + HCl(aq) -->



Which of the following reactions is NOT a redox reaction?

2Cu(s) + O2(g) --> 2CuO(s)
Mg(s) + 2HCl(aq) --> MgCl2(aq) + H2(g)
Zn(s) + FeBr2(aq) --> Fe(s) + ZnBr2(aq)
CH4(g) + 2O2(g) --> CO2(g) + 2H2O(g)
all are redox reactions

Which of the following is NOT a common driving force in metathesis reactions?

precipitation
the transfer of electrons
evolution of a gas
formation of a weak or nonelectrolyte
none of these are driving forces

The volume of a 3.72 M Na3PO4 solution needed to prepare 2.50 x 102 mL of a 1.43 M Na+ solution is:

24.0 mL
32.0 mL
48.1 mL
96.1 mL
Cannot be answered because this is an impossible solution to prepare.

The oxidation numbers for all the elements in each compound are correct EXCEPT for:

Fe2(CrO4)3 ; Fe: +3; Cr: +6; O: -2
Mn(ClO3)2 ; Mn: +2; Cl: +5; O: -2
HgCr2O7 ; Hg: +2; Cr: +6; O: -2
HClO4 ; H: +1; Cl: +7: O: -2
Co3(PO4)2 ; Co: +2; P: +4; O: -2

As a new technician in a quality control lab you have just been assigned to prepare 0.100 M NH3 solutions in each of five, separate 1000-mL volumetric flasks. You will do this by adding a measured volume of 14.8 M NH3 to each and then filling the flasks with H2O up to the mark on the neck of the flask. The volume of 14.8 M NH3 that you will add to each flask is:

0.676 mL
6.76 mL
67.6 mL
1.48 mL
14.8 mL

After 111 mL of 0.111 M NaOH and 111 mL of 0.111 M H2SO4 are mixed, assuming that the volumes are additive, the concentration of H+ is:

0.0555 M
0.111 M
0.222 M
0.333 M
none of these

You are assigned the task of standardizing a NaOH solution that was prepared by the technician who quit his job the day before you started work as an intern. You decide to use the titration technique and then make a list of measurements and information that you will need to accomplish the assignment. Which of the following will you need to complete the calculations for the assignment?

balanced chemical equation for reaction between acid and base
mass and chemical formula of a known acid
mass and MW of NaOH the technician used to prepare the solution
total volume of NaOH solution that the technician prepared
volume of NaOH solution needed to turn the solution pink

i, ii and v.
i, iii, and iv
ii and v.
ii, iii, and iv.
all the above would be needed to determine the concentration of NaOH

Which of the following species is considered insoluble in pure H2O?

KCl
(NH4)2S
NH4Br
SrSO4
All of the above are considered soluble.

Given a solution containing both silver acetate and copper(II) acetate you wish to add another solution such that one of the two above cations will precipitate, while the other will remain in solution. Of the aqueous solutions below, which will do what you wish?

KCl
KNO3
KOH
K2S
none of these

Which of the following species will NOT convert Sn2+ to Sn metal?

Ca
Mn
Co
Pb
All of these will convert Sn2+ to Sn.

How many moles of NaOH are in 22.0 mL of 0.150 M NaOH?

0.00148
0.00221
0.00330
1.48
3.30

Which of the following sets is a weak acid and weak base, respectively?

HClO4, NH3
HF, Ca(OH)2
HCl, LiOH
H2CO3, NH3
HBr, NaOH

What is the concentration of an HCl solution if 22.0 mL required 43.2 mL of a 0.100 M NaOH solution to reach the endpoint?

0.196 M
5.09 M
0.00432 M
0.000509 M
0.100 M

All of the following are strong electrolytes in aqueous solution except:

H2CO3
H2SO4
KOH
NaCl
HCl

An antacid tablet containing 0.50 g NaHCO3 (molar mass = 84.01 g) is dissolved in water. The total volume of solution is 250 mL. What is the molarity of this NaHCO3 solution?

0.024 M
4.1 M
2.22 x 10-4 M
0.0060 M
0.0041M

Which of the following ionic compounds is insoluble in water?

NH4Cl
AgNO3
PbSO4
KI
Na2S

In accordance with solubility rules, which of the following is true when solutions containing Pb(NO3)2(aq) and KI(aq) are mixed?

KNO3 will precipitate; Pb2+ and I- are spectator ions.
No precipitate will form.
Pb(NO3)2 will precipitate; K+ and I- are spectator ions.
PbI2 will precipitate; K+ and NO3- are spectator ions.
Pb2+ and I- are spectator ions and PbI2 will precipitate.

How many moles of NH3 are produced from 5.0 moles of H2 with excess N2?

N2 + 3H2 --> 2NH3

2.0
3.0
5.0
3.3
7.0

Identify the major ions present in an aqueous solution of NaOH.

Na2+, O- , H-
Na+, OH-
NaO- , H+
Na+, O2- , H+
Na- , OH+

Which of the following is not a characteristic of an acid?

a sour taste.
turns litmus paper red.
feels slippery.
reacts with most metals to release H2.

40.0 mL of a HCl solution with concentration of 0.60 M is to be diluted to a concentration of 0.10 M. What would be the final volume after dilution?

6.67 mL
667 mL
240 mL
60.0 mL
500 mL

The distinguishing characteristic of all electrolyte solutions is that they:

contain molecules.
conduct electricity.
react with other solutions.
always contain acids.
conduct heat.

Using the following activity series, which of the following reactions will take place?



2Na + 2H+ --> 2Na+ + H2
Cu + 2H+ --> Cu2+ + H2
Ni2+ + Cu --> Ni + Cu2+
3Ag+ + Au --> 3Ag + Au3+
Cr3+ + 3Ag --> Cr + 3Ag+

Which of the following is insoluble?

AgI
Na2SO4
KNO3
NaOH
CH3COOH

When ammonia (NH3) is added to water, what are the products in the reaction?

H+, NH4+
OH-, NH4+
H2O, NH4OH
H+, OH-
no reaction occurs

In the following reaction, which are considered spectator ions?

2HCl(aq) + Na2S(aq) --> H2S(g) + 2NaCl(aq)

H+, S2-
H+, Cl-
Na+, Cl-
S2-, Cl-
Na+, H+

Zn(OH)2 solid (molecular mass = 99.41 amu) is added to 0.400 L of 0.550 M HBr. The resultant solution which is acidic, requires 165 mL of 0.500 M NaOH for neutralization. The mass (in mg) of Zn(OH)2 that was originally added was numerically:

6.83 mg
82.5 mg
138 mg
6830 mg
None of the above are close to the correct answer.

Which unbalanced oxidation-reduction reaction is possible?

Al3+ + Fe2+ --> Al + Fe3+
Al3+ + Fe2+ --> Al + Fe
Al + Fe2+ --> Al3+ + Fe3+
Al + Fe --> Al3+ + Fe3+
Al3+ + Fe3+ --> Al + Fe

After 111 mL of 0.111 M HNO3 and 111 mL of 0.111 M Ca(OH)2 are mixed, assuming the volumes are additive, the concentration of OH- ion is:

0 M (sufficient acid has been added to neutralize the base).
0.0555 M
0.111 M
0.222 M
0.333 M

Which of the following elements will convert Cr3+ to Cr metal?

Mg
Co
Pb
Ag
None of these will convert Cr3+ to Cr.

How many mL of 0.627 M NaOH will be required to prepare 100.0 mL of 0.0725 M NaOH?

5.78
11.6
23.1
46.3
None of these

Considering what is a strong, weak or non-electrolyte, which of the rows in the following table is completely correct?


CuSO4 KOH C2H5OH HC2H3O2 HNO3 C12H22O11
(a) strong strong non strong weak non
(b) strong strong strong weak strong non
(c) weak strong weak weak strong non
(d) strong strong non weak strong non
(e) strong weak non weak strong weak


Which of the following is(are) a driving force(s) for a chemical reaction to occur in aqueous solution?

A gas forms.
A precipitate forms.
An ion-dipole interaction forms.
A weak acid or base forms.
All of the above serve to drive the reaction.

When 25.0 mL of 0.400 M H2SO4 and 50.0 mL of 0.850 M H2SO4 are mixed, what is the molarity of sulfuric acid in the final solution?

0.350 M H2SO4
0.700 M H2SO4
3.50 M H2SO4
7.00 M H2SO4
10.0 M H2SO4

Almost all sulfides are water insoluble. Exceptions include:

FeS
CuS
CdS
SrS
HgS

What are the spectator ions in the following reaction/equation?

Pb(NO3)2(aq) + Na2SO4(aq) --> PbSO4(s) + 2NaNO3(aq)

Pb2+, SO42-
Pb2+, NO3-
Na+, NO3-
Na+, SO42-
Na+

Identify which one of the following constitutes an aqueous 1.0 M NaCl solution:

1.0 L of aqueous solution containing 100 g NaCl
500 mL of aqueous solution containing 58.44 g NaCl
an aqueous solution containing 5.844 mg NaCl per 1 mL
5.00 L of aqueous solution containing 292.2 g NaCl
58.44 g NaCl added to exactly 1 L of pure water

The next two questions refer to a solution made by dissolving 0.5103 g of a solid diprotic acid in enough pure water to make 50.00 mL of solution; 10.00 mL of this solution is completely neutralized by 18.75 mL of 0.0725 M NaOH.

The molarity of the acid solution is numerically:

0.0340
0.0680
0.0725
1.36
none of the above

The molecular mass of the acid (in amu) is numerically:

7.50 x 101
1.50 x 102
3.00 x 102
7.50 x 102
none of these

In the lab 7.58 g of barium nitrate Ba(NO3)2 (molar mass = 261.36) is dissolved in enough water to form 0.850 L of solution. A 0.100 L sample is withdrawn from this stock and titrated with a 0.051 M solution of K2SO4. What volume of K2SO4 solution is required to preciptate all the Ba2+ as BaSO4?

0.033 L
0.067 L
0.134 L
0.167 L
0.240 L

Which of the following describes what occurs between Zn(s) and Mn2+ in aqueous solution?

Zn is a reducing agent.
Zn is oxidized.
Mn2+ is an oxidizing agent.
All of the above are true.
No reaction occurs.

Which of the following will NOT reduce Fe2+ to Fe?

Na
Pb
Zn
Cr
All of these will reduce Fe2+ to Fe.

In the following balanced equation,

6I-(aq) + 14H3O+(aq) + Cr2O72-(aq) --> 2Cr3+(aq) + 21H2O(l) + 3I2(s)
the reducing agent (that is, the substance oxidized) is:


H3O+
H+
Cr2O72-
I-
H2O

In which of the following reactions does the lead reactant species act as a reducing agent?

Pb + 1/2O2 --> PbO
PbO + C --> 2Pb + CO
PbS + 3/2O2 --> PbO + SO2
2Al + 3PbO --> Al2O3 + 3Pb
none of the above

In a lecture demonstration, magnesium metal was given sufficient energy to burn in air. The metal continued to burn even after it was covered with dry ice, solid CO2:

2Mg(s) + CO2(s) --> 2MgO(s) + C(s)
In the reaction of Mg with CO2:


Carbon is oxidized, oxygen is reduced.
Oxygen is oxidized, carbon is reduced.
Oxygen is oxidized, Mg is reduced.
Mg is oxidized, oxygen is reduced.
Mg is oxidized, carbon is reduced.

In a class demonstration we titrated 1.00 x 102 mL of 0.100 M of Ba(OH)2 with 1.00 M H2SO4. The balanced equation is:

Ba(OH)2(aq) + H2SO4(aq) --> BaSO4(s) + 2H2O(l)
What volume of the H2SO4 solution did we add to neutralize the Ba(OH)2? Remember that we used conductivity (light bulb) as an indicator.


5 mL
10 mL
20 mL
100 mL
200 mL

What is the oxidation number of phosphorus in K3PO3?

-6
+1
-3
+3
+6

What is the oxidation number for iodine in KIO4?

+7
+3
0
-3
-7

Calculate the molarity of an ammonia solution that contains 252.9 g of NH3 in 2.52 L of solution.

1.00 M
5.89 M
14.8 M
25.2 M
100.0 M

What is the molarity of CH3OH in a solution prepared by dissolving 11.7 g of CH3OH in enough water to make a 250. mL solution?

11.9 M
1.59 x 10-3 M
0.0841 M
1.46 M
46.8 M

Which of the following is a weak acid?

HNO3
HCl
HI
HClO4
H2SO3

What are the spectator ions in the reaction between KOH and HNO3?

KOH(aq) + HNO3(aq) -->

K+ and H+
H+ and OH-
K+ and NO3-
H+ and NO3-
all ions are spectator ions because there is no reaction

Which of the following is an insoluble compound?

Na2CO3
AgNO3
FeSO4
Na2S
SrCO3

What is the concentration of an HI solution if 75.0 mL of the acid required 35.21 mL of 0.1894 M KOH to reach the endpoint in the titration?

0.2668 M
0.8003 M
0.08892 M
0.1345 M



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Answers
C
B
C
B
C
E
D
B
D
B
A
D
A
A
C
B
C
B
C
E
C
E
E
B
E
E
B
B
E
B
A
A
D
A
D
C
D
A
A
A
C
D
D
B
C
C
B
A
A
B
C
D
A
B
A
B
D
E
B
D
C
D
B
B
B
E
B
D
A
E
B
D
A
B
D
E
C
E
C

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