CHEMISTRY CHAPTER 2

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Exercise 2.50: Problems by Topic – Atomic Theory, Nuclear Theory, and Subatomic Particles

Which of the following statements about subatomic particles are false?

Part A

Protons and electrons have charges of the same magnitude but opposite sign.

[removed]True

[removed]False

Part B

Protons have about the same mass as neutrons.

[removed]True

[removed]False

Part C

Some atoms don’t have any protons.

[removed]True

[removed]False

Part D

Protons and neutrons have charges of the same magnitude but opposite sign.

[removed]True

[removed]False

Exercise 2.58: Problems by Topic – Isotopes and Ions

Uranium-235 is used in nuclear fission.

Part A

Determine the number of protons and neutrons in uranium-235.

Enter your answers numerically separated by a comma.

N p , N n = 

 

 

Part B

Write its symbol in the form AZ X .

Express your answer as an isotope.  

 

Exercise 2.60: Problems by Topic – Isotopes and Ions

Determine the number of protons and electrons in each of the following.

 

Part A

Zn 2+

Enter your answers numerically separated by a comma.

N p , N e = 

 

 

Part B

P 3−

Enter your answers numerically separated by a comma.

N p , N e = 

 

 

Part C

Fe 3+

Enter your answers numerically separated by a comma.

N p , N e = 

 

 

Part D

Sr 2+

Enter your answers numerically separated by a comma.

N p , N e = 

 

 

 

Exercise 2.74: Problems by Topic – The Periodic Table and Atomic Mass

Silicon has three naturally occurring isotopes with the following masses and natural abundances:

Isotope

Mass (amu)

Abundance (%)

Si−28

27.9769

92.2

Si−29

28.9765

4.67

Si−30

29.9737

3.10

Part A

Calculate the atomic mass of silicon.

Atomic mass = 

 

 

 

Exercise 2.79: Problems by Topic – The Mole Concept

Part A

How many sulfur atoms are there in 4.5 mol of sulfur?

Express your answer using two significant figures.

 

 

 

 

Exercise 2.81: Problems by Topic – The Mole Concept

What is the amount, in moles, of each of the following substances?

 

Part A

12.2 g Ar

 

 

Part B

3.75 g Zn

 

 

Part C

26.6 g Ta

 

 

Part D

0.219 g Li

 

 

 

Exercise 2.82: Problems by Topic – The Mole Concept

What is the mass, in grams, of each of the following?

Part A

2.3×10−3 mol Sb

Express your answer using two significant figures.

 

 

 

Part B

3.53×10−2 mol Ba

Express your answer using three significant figures.

 

 

 

Part C

43.6 mol Xe

Express your answer using three significant figures.

 

 

 

Part D

1.1 mol W

Express your answer using two significant figures.

 

 

 

 

Exercise 2.76: Problems by Topic – The Periodic Table and Atomic Mass

The atomic mass of copper is 63.546 amu

 

Part A

Do any copper isotopes have a mass of 63.546 amu ?

[removed]yes

[removed]no

Part B

Explain.

Exercise 2.36: Problems by Topic – The Laws of Conservation of Mass, Definite Proportions, and Multiple Proportions

Upon decomposition, one sample of magnesium fluoride produced 1.65 kg of magnesium and 2.57 kg of fluorine. A second sample produced 1.31 kg of magnesium.

 

Part A

How much fluorine (in grams) did the second sample produce?

 

 

 

 

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