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stem chemistry acount

Total questions: 20

Worksheet time: 41mins

Name
Class
Date
1.
How many gram is 0.5 mol of Copper atoms? (Cu:63,5g/mol)
a)
63,5 g
b)
6,35 g
c)
31,75 g
d)
3,175 g
2.
What is the mol number of 250 g CaCO? (Ca:40g/mol, C:12g/mol, O:16g/mol)
a)
1,5 mol
b)
1 mol
c)
2 mol
d)
2,5 mol
3.
What is the mass of 0.2 mol of Al? (Ag:27g/mol)
a)
27 g
b)
54 g
c)
5,4 g
d)
2,7 g
4.
B2H6 + 3O2 -->2 HBO2 + 2 H2O
 What mass of O2 will be needed to burn 36.1 g of B2H6?
a)
13.8 g O2
b)
3.86 mol of O2
c)
124 g O2
d)
12.4 g O2
5.
4 Al + 3 O2 –> 2 Al2O How much aluminum would be needed to completely react with 45 grams of O2?
a)
1.05 moles
b)
3.75 moles
c)
1.875 grams
d)
1.875 moles
6.
N2 +  3H2 −->  2NH3 
How many moles of hydrogen are needed to react with 2 moles of nitrogen?
a)
6
b)
2
c)
3
d)
1
7.

How many moles are 98.3 grams of aluminum hydroxide, Al(OH)3? (Ar Al=27, H=1, O=16)

a)

1.26 moles

b)

0.8 moles

c)

7,673.4 moles

d)

150 moles

8.

2.46 g of sodium hydroxide (molar mass = 40) is dissolved in water and the solution is made to 100 cm3 in a volumetric flask. The molarity of the solution is:

a)

3.14 M

b)

0.04 M

c)

0.615 M

d)

4.2 M

9.

The molality of a solution containing 20.7 g of potassium carbonate dissolved in 500 mL of solution:


(assume density of solution =1 g mL–1).

a)

3.13 m

b)

0.313 m

c)

31.3 m

d)

None of the above

10.

How many grams of Na2CO3 should be dissolved to make 100 cm3 of 0.15 M Na2CO3 solution?

a)

3.6 g

b)

1.59 g

c)

2.80g

d)

4.32 g

11.

250 mL of 1.5 M solution of sulphuric acid is diluted by adding 5L of water. The molarity of the diluted solution is:

a)

0.0926

b)

0.0823

c)

0.0714

d)

12

12.
Which of the following word pairs correctly completes the sentence below?
_______ are corrosive substances characterized as having a strong smell, a sour taste, and a _______.
a)
Acids; pH less than 7
b)
Acids; pH greater than 7
c)
Bases; pH greater than 7
d)
Bases; pH less than 7
13.

Benjamin, Evelyn, and Kai are working on a science project. They found an unknown substance in a beaker in their school lab. They want to determine the relative pH of the unknown substance. Benjamin places a piece of blue litmus paper into the substance, and the litmus paper stays blue.
The substance in the beaker

a)

is a base.

b)

has a neutral pH.

c)

is an acid.

d)

there is not enough information here to give a definitive answer

14.
If the pH of a solution is 5.6 the pOH is
a)
6.5
b)
12.4
c)
8.4
d)
5.6
15.
If the [OH-] of a solution is 2.7 x 10-4 mol/L the pOH of the solution is
a)
10.44
b)
3.56
c)
1.00
d)
-4.43
16.

If we dissolve 20.0 grams of HCl in 1.2 L of water, what is the pH of that solution?

a)

0.34

b)

4.21

c)

7.20

d)

10.34

17.
If the [H+] of a solution is 6.8 x 10-9 mol/L the pH is
a)
8.17
b)
8.2
c)
9.99
d)
8.62
18.
if the [H+] of a solution is 8.4 x 10-3 mol/L the pOH of the solution will be
a)
2.08
b)
11.92
c)
1.02
d)
12.98
19.

The Kw at room temperature (25 degrees C) is equal to 1.0 x 10-14.  It can also be defined as:

a)

the pH and pOH of a solution

b)

the product of the hydronium ion and the hydroxide ion concentrations

c)

-log [hydronium ion]

d)

antilog -pH

20.

If a solution has a [OH-] of 2.3x10-4, it must be a(n)...

a)

Acid

b)

Base

c)

Neutral

d)

salt