🏷️ LIMITED TIME OFFER: GET 20% OFF GRADE+ YEARLY SUBSCRIPTION →
Log in
HomeClass Notes1,200,000US530,000

CAS CH 101 Lecture Notes - Lecture 3: Iron(Iii) Oxide, Unified Atomic Mass Unit, Molar Mass

110 views5 pages
bluecricket168
4 Dec 2017
School
Boston University
Department
Chemistry
Course
CAS CH 101
Professor
Binyomin Abrams

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Stoichiometry - the study of quantities of materials consumed and produced in chemical reactions. Atoms are so small, it is difficult to discuss how much they weigh in grams. Use atomic mass units. an atomic mass unit (amu) is one twelth the mass of a carbon-12 atom. The decimal numbers on the table are atomic masses in amu. Elements occur in nature as mixtures of isotopes. A substance"s molar mass (molecular weight) is the mass in grams of one mole of the compound. [n = integer] molecular formula = c6h6 = (ch)6 empirical formula = ch. Empirical formula determination: base calculation on 100 grams of compound (change percents into # of grams), determine moles of each element, divide each value of moles by the smallest of the mole. If result is not in whole numbers, multiply each number by an integer to obtain all whole numbers.

Get access

Grade+20% off
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers

Related Documents

CAS CH 101
Final Exam
Study Guide
CAS CH 101 Study Guide - Midterm Guide: Planck Constant, International System Of Units, Atomic Number
bluemole23
CHEM 1A Chapter Notes - Chapter 3: Mass Spectrometry, Molar Mass, Chemical Formula
tealmosquito158
CHM 111 Chapter Notes - Chapter 3: Mass Spectrometry, Limiting Reagent, Unified Atomic Mass Unit
whiteminnow603

Related Questions

Determine the empirical and molecular formulas of each of the following substances:

(a) Styrene, a compound substance used to make Styrofoam® cups and insulation, contains 92.3% C and 7.7% H by mass and has a molar mass of 104 g/mol.

(b) Caffeine, a stimulant found in coffee, contains 49.5% C, 5.15% H, 28.9% N, and 16.5% O by mass and has a molar mass of 195 g/mol.

(c) Monosodium glutamate (MSG), a flavor enhancer in certain foods, contains 35.51% C, 4.77% H, 37.85% O, 8.29% N, and 13.60% Na, and has a molar mass of 169 g/mol.

Empirical formula of this compound is CH.

To determine the molecular formula, we need to find out how many times is molar mass higher than the mass of empirical formula:

Molecular formula is C8H8.

b) Empirical formula of caffeine:

Empirical formula of caffeine is C4H5N2O. The sum of atomic masses from empirical formula is 97 g/mol.

Molecular formula of caffeine is 2 × empirical formula = C8H10N4O2

c) Empirical formula of MSG:

Empirical formula of MSG is C5H8NO4Na. The sum of atomic masses of empirical formula is 169 g/mol, the same as molar mass. Empirical and molecular formula are identical.

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