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CHM110H5 Lecture Notes - Lecture 2: Mass Spectrometry, Molar Mass, Unified Atomic Mass Unit

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skyhyena767
2 Dec 2015
School
UTM
Department
Chemistry
Course
CHM110H5
Professor
Judith C Poe

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Document Summary

Carbon is assigned a mass of exactly 12 atomic mass units, and the masses of all other atoms are given relative to this standard. Mass spectrometer used to compare the masses of atoms. Atomic masses are usually the average values of all the isotopes. The mass of 1 mole of an element is equal to its atomic mass in grams. Mole the number equal to the number of carbon atoms in exactly 12 grams of pure 12c. 1 mole of seconds represents a span of time 4 million times as long as the earth has already existed. 1 mole of marbles is enough to cover the earth to a depth of 50 miles. Molar mass mass in grams of 1 mole of a compound. In this text, for convenience, we will apply the term molar mass to both ionic and molecular substances i. e. we will refer to 58. 44 as the molar mass for nacl.

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Related Questions


There are two stable isotopes of supposium (Su). Su-191=190.9609u(27.30%) Su-194=193.9633 u(72.70%) Compute the atomic mass ofsupposium.
a. 194.0 u b. 193.1 u c. 191.8 u d. 190.9 u e. 192.5 u

Which would not be found with a mass spectrometer.
a. the atomic mass of a single isotope of potassium
b. the number of stable isotopes of potassium c.the mass of aproton
d. the number of protons in potassium e. the relative abundance oftwo isotopes of potassium

How many protons, neutrons, and electrons are in 24 Mg2+?
12
a. 10 protons, 12 electrons, 24 neutrons b. 12 protons, 10electrons, 12 neutrons
c.12 protons, 12 electrons, 24 neutrons d. 24 protons, 10electrons, 12 neutrons
e. 12 protons, 12 electrons, 12 neutrons


1.The age of rocks is sometimes calculated from the measured excessof lead 206 atoms over the normal abundance. The uranium isotopeU-238 decays to lead-206.What is the percent abundance of lead-206if there aare 4.52 X 10^21 atoms of lead-206 in a 198 g sample ofore that is 2.58% lead? a. 27.7 b. 0.0202 c. 4.70 x 10^-3 d. 30.4e. 0.782

2. The average atomic mass of B is 10.80 u. Boron has only twostable froms 10
5 B(10.00 u) and 11
5 B (11.00 u). What is the natural percent abundance of B?
a. 1.0% b. 20% c. 75% d. 3.8% e. 80%

3. 57.7 g Ni contains how many atoms? a. 3.47x10^23 b.0.983 c. 1.24x 10^24
d. 6.13x10^23 e. 5.92x10^23


4. What mass of magnesium is necessary to make 10.5 g of magnesiumbromide if 1.04 g of magnesium makes 7.88 g of magnesiumbromide?
a. 7.89 g b. 1.39 g c. 79.9 g d. 3.66 g e. 1.58 g



5. How many atoms of lead are required to cover a 33.0 cm by 45.0cm area witha sheet of lead that is 0.140 mm thick? The density oflead is 11.35 g/cm3.
a. 1.42x10^26
b. 2.29x10^25
c. 6.86x10^22
d. 2.29x10^26
e. 6.86X10^23

6. The natural abundance of calcium in the earth's crust is 3.4% bymass. How many calcium atoms are present in a 1.50 g sample of theearth's crust?
a. 7.7x10^22 b. 7.7x10^20 c. 3.1x 10^22 d.6.6x10^23 e.5.1x10^20


9.Rubidium possesses two stable forms and has an average mass of85.5. 85Rb has a mass of 84.9 and a percent abundance of 72.2%.What is the mass of the other form of Rb?

a. 85.7 u
b. 88.3 u
c. 86.1 u
d. 89.4 u
e. 87.1 u

10. Which is the more abundant isotope, CI-35 or CI37?
a. CI-17
b. CI-37
c. The two isotopes are equal in balance
d. CI-35
e. A third unstable isotope is more abundant

11. An element has 5 stable isotopes. The mass and percentage ofeach are:
69.9243 20.52%
71.9217 27.43%
72.9234 7.76%
73.9219 36.54%
75.9214 7.76%
The element is which of the following
a. Se b. Ge c. Ga d. As e. Zn

12. Lead-206 has a relative abundance of 23.6%. What sized block oflead (in cubic centimeters) will contain 8.34x10^21 atoms oflead-206? The density of lead is 11.35 is g/cm3.
a. 0.253
b. 0.0107
c. 1.07
d. 12.1
e. 0.330

13. When decomposed chemically, 73.0 grams of a sample of HCIproduce 71.0 g of Cl2 and 2.0 g of H2, while 34.0 g of a sample ofH2s produce 32.0g of S and 2.0g of H2. This is an example of theLaw:
a. of Definate Proportions
b. E=mc^2
c. of multiple proportions
d. of Conservation of Mass
e. none of these

Having trouble with thse questions. Please answer all questions correctly. Will provide a thumbs up.

1.Which of these equations is the balanced reaction between nitrous acid solution and solidmagnesium hydroxide ?

A.2NH3(aq) + MgOH (s) Mg(NH4)2(aq) + 2 H2O(l)

B.2HNO2(aq) + Mg(OH)2(s) Mg(NO2)2(aq) + 2 H2O(l)

C.2HNO3(aq) + Mg(OH)2(s) Mg(NO3)2(aq) + 2 H2O(l)

D.2HNO2(aq) + MgOH (s) Mg(NO3)2(s) + 2H2O(l)

2.Balance the following chemical equation:

C3H7OH(l) + O2(g)CO2(g) + H2O(g)

a. C3H7OH(l) + 4 O2(g)3 CO2(g) + 4 H2O(g)

b.2 C3H7OH(l) + 9 O2(g)6 CO2(g) + 8 H2O(g)

c.C3H7OH(l) + 5 O2(g)3 CO2(g) + 4 H2O(g)

d.C3H7OH(l) + O2(g)CO2(g) + H2O(g)

3.Which species would be considered a spectator ion based on the following equation?

Ba2+ + 2NO3− + 2Na+ + SO42- → BaSO4(s) + 2NO3− + 2Na+

SO42-

2NO3−

Ba2+

BaSO4

4.Barium sulfate is often ingested to aid in the diagnosis of GI tract disorders. The equation for its production is Ba2+ + SO42- → BaSO4(s). What type of equation is this?

A full equation

A net ionic equation

A total ionic equation

An oxidation-reduction equation

5.Which species is being reduced in this reaction?

CuO(s) + H2(g) Cu(s) + H2O(g)

H2O

CuO

Cu

H2

6.Which of the following is an oxidizing agent?

H2

NH3

O2

H2O

7.The following chemical equation,

HC2H3O2(aq) + KOH(aq) KC2H3O2(aq) + H2O(l),

is an example of a(n) _______ reaction.

a.oxidation-reduction and acid-base

b.acid-base

c.precipitation

d.oxidation-reduction and precipitation

e.oxidation-reduction

8.What substance is oxidized in the following reaction?

4HCl + MnO2 → Cl2 + 2H2O + MnCl2

a.Mn in MnO2

b.O in MnO2

c.Cl in HCl

d.H in HCl

9.What is the reducing agent in the following reaction?

4HCl + MnO2 → Cl2 + 2H2O + MnCl2

Cl2

MnCl2

HCl

MnO2

10.All redox reactions involve oxygen.

True

False

11.The term formula weight can be used with respect to which of the following?

A.ionic compounds

B.covalent compounds

C.both a and b

D.neither a nor b

12.What is the molecular weight of ibuprofen, C13H18O2?

A.206.3 amu

B.377.7 amu

C.29.0 amu

D.289.4 amu

13.The mass of an atom of 12C is exactly 12 atomic mass units. Which of the following describes a mole of 12C atoms?

A.a sample which weighs exactly 12 atomic mass units

B.a sample which contains 6.02 × 1023 atoms of 12C

C.both a and b

D.neither a nor b

14.The mass of an atom of 12C is exactly 12 atomic mass units. Which of the following describes a mole of 12C atoms?

A.a sample which contains 6.02 × 1023 atoms of 12C

B.a sample which weighs exactly 12.011 grams

C.both a and b

D.neither a nor b

15.What is the molar mass of water, H2O?

A.18.02 g

B.18.02 amu

C.17.01 g

D.17.01 amu

16.What is the molar mass of glucose, C6H12O6?

A.180.2 amu

B.180.2 g

C.60.05 amu

D.60.05 g

17.In the reaction 2H2O → 2H2 + O2, 2.0 mol water will produce how many grams of O2?

32

64

16

36

18.In the reaction 2CH4 + O2 → 2CO + 4H2, how many molecules of CO will be produced by the complete reaction of 1.60 grams of CH4?

3.01 × 1022

2.00

12.0 × 1023

6.02 × 1022

19.Suppose 2.43 g of magnesium is reacted with 3.20 g of oxygen: 2Mg + O2 → 2MgO. How many grams of MgO will be produced?

1.27

4.03

5.63

8.06

20.Which of the following conversion factors would allow one to calculate the amount of PbI2produced from a given amount of NaI in the following unbalanced reaction?

Pb(NO3)2 + Nal → Pbl2 + NaNO3

a.

b.

c.

d.

21.The unbalanced equation for the reduction of copper(I) sulfide with oxygen is given below. What mass of copper is produced from the reduction of 7.50 g Cu2S?

Cu2S(s) + O2(g) Cu(s) + SO2(g)

18.8 g

5.99 g

1.50 g

9.39 g

2.99 g

22.How many grams of aluminum oxide are produced by the complete reaction of 19.8 g aluminum with excess oxygen?

10.5 g aluminum oxide

37.4 g aluminum oxide

49.9 g aluminum oxide

74.8 g aluminum oxide

23.If 5 grams of CO and 5 grams of O2 are combined according to the reaction, which is the limiting reagent?

2CO + O2 → 2CO2

O2

CO and O2

CO2

CO

24.In an industrial process, nitrogen is reacted with hydrogen to produce ammonia. The percent yield of this particular process is 26%. How much hydrogen is needed to produce 4.8 kg ammonia?

1.5 kg

7.0 kg

0.85 kg

3.3 kg

25.A percentage yield greater than 100% has been reported in a scientific paper you are assigned to read. What would be a reasonable explanation for this?

a. The product was measured more than once.

b. It must be a typographical error since yields can't exceed 100%.

c. A lack of training of the professor who published the study.

d. Small measurement errors could have caused this to occur.

26.In an industrial process, nitrogen is reacted with hydrogen to produce ammonia. The percent yield of this particular process is 24.8%. How much hydrogen is needed to produce 3.7 kg ammonia?

1.8 kg

1.2 kg

4.4 kg

12 kg

2.7 kg

27.The following reaction has a percent yield of 90.5%. How many grams of carbon dioxide are produced from 78.5 g calcium carbonate via this reaction?

2 HNO3(aq) + CaCO3(aq) Ca(NO3)2(aq) + H2O(l) + CO2(g)

34.5 g

21.6 g

38.1 g

31.2 g

28.When gas molecules dissolve in liquids to form a saturated system, the process is usually

exothermic.

endothermic.

independent of the nature of the liquid.

temperature independent.

29.The reaction below would be considered.

CaCO3 + heat → CaO + CO2

an exothermic combination.

an exothermic decomposition.

an endothermic combination.

an endothermic decomposition.

30.The combustion of one mole of propane, C3H8, releases 531 kcal. How much heat is released by the combustion of 1.20 moles of propane?

A.584 kcal

B.690 kcal

C.443 kcal

D.637 kcal

31.The combustion of one mole of propane, C3H8, releases 531 kcal. How much heat is released by the combustion of 4.40 g of propane?

A.531 kcal

B.5.31 × 104 kcal

C.53.1 kcal

D.5.31 × 103 kcal

32.Metabolism of one mole of glucose, C6H12O6, releases 670 kcal. How much heat is released by the combustion of 0.300 moles of glucose?

A.201 kcal

B.2.41 × 103 kcal

C.186 kcal

D.2.23 × 103 kcal

33.Metabolism of one mole of glucose, C6H12O6, releases 6.70 × 102 kcal. How much heat is released by the combustion of 50.0 g of glucose?

A.201 kcal

B.2.41 × 103 kcal

C.186 kcal

D.2.23 × 103 kcal