Chemistry ?'s?

Question

Is it A B C D or E

This isn't HW, its suppose to help me for the test, the #'s are going to b different but in the same format. so how do u solve them? Thank you sooo MUCH

1) To prepare exactly 200. ml of a 5.00M solution of calcium chloride(CaCI2) solution ___g of the ssalt would be required

A 1.11

B 75.5

C 111

D 250

2) the mass % of the solute in a solution containing 5.85 g of sodium chloride in 100.g of water is

A 5.53%

B 94.5%

C 5.85%

D 0.100%

3) acid rain is a problem because ___

A it reacts with metals

B it reacts with marble

C it changes the pH of lakes

D none of the above

E all of the above

4) If the oxidation number of an element changes from -1 to +1, the element has been reduced

A true

B false

5) it would require ____ ml of 0.300 M hydrochloric acid solution to neutralize 30.0 ml of 0.300M sodium hydroxide solution

A 15,0

B 40.0

C 30.0

D 10.0

E 20.0

Thanks a lot :)

Answer 1

1)Molarity = number of moles/volume of solution in L

Number of moles= Molarity * vol. in L

= 5.00M * 0.200 L = 1.00 mol CaCl2

Molar mass(mass of 1 mol) of CaCl2 = 40.08 + 2*35.45 = 110.98 g

So mass of 1.00 mol CaCl2 = 1*110.98 = 111 g, corrected to the correct number of significant figures. So the answer is C.

2) mass% of solute = [mass of solute/(mass of slute + mass of solvent)] *100

Here, sodium chloride is solute, and water is solvent

mass% of solute = [5.85 g/(5.85 g+100.g)]*100 = 5.53%

So the correct choice is A.

3) E

4)Oxidaton can be defined as the increase in oxidation number, and reduction is the decrease in oxidation number. If the oxidation number of an element changes from -1 to +1, the oxidation number increases from -1 to +1. So the element has been oxidized. The statement is false. Answer is B.

5)The neutralization reaction is

HCl + NaOH ------> NaCl + H2O

1 mol HCl neutralizes 1 mol NaOH

Since the molarity(concentration) of both HCl and NaOH solutions are the same, their volumes must also be the same in order for them to neutralze completely. So volume of HCl is 30.0mL. The corect choise is C.

Answer 2

Im not going to do them but I will tell you what to do.

1. MolarityX vol=mol X Molecular weight= grams

2. 5.85/ (total mass of solution)

3. acids increas H+ concentration, and forms a salt with metal hydroxides so do you think it reacts with marble if so i will be ........

4. gain electron oxidize lose electron reduce

5. MVbase=MVacid solve for V based on the equation!

I've haven't done it for you but gave you some clues!

Answer 3

To ensure taht there is no confusion with the answer from blazingd, pse note:

LOSS of electrons = OXIDATION

GAIN of electrons = REDUCTION

Qestion 4: to go from -1 to +1 indicates that the element has lost (negative) electrons,  therefore it must have been oxidised.