CH 104 Lecture Notes - Lecture 5: Molar Mass, Unified Atomic Mass Unit, Reagent

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taneel75

15 Jan 2017

School

University of Alabama

Department

Chemistry

Course

CH 104

Professor

Stephen Woski

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Document Summary

Atoms in the reactants and products must equal eachother. Formula weight the number of a thing that makes up a mole of that thing. Conversion: 1 mol/6. 02 x 10^23 or 6. 02 x 10^23/1 mol. 1 mol of carbon weighs 12. 01 g calculate formula weight by writing the formula and determining the number of atoms of each element from the subscripts. Ii. multiply the number of atoms of each element by the atomic weight and add the results. Mass to moles calculation mass (g) x mol/g = moles moles x g/mole = mass (g: identify the original and desired quantity, write out conversion factors, set up and solve the problem.

Related Questions

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^â + 2Na⁺ + SO₄^2- â BaSO₄(s) + 2NO₃^â + 2Na⁺

SO₄^2-

2NO₃^â

Ba²⁺

BaSO₄

4.Barium sulfate is often ingested to aid in the diagnosis of GI tract disorders. The equation for its production is Ba²⁺ + SO₄^2- â 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

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 â 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 â 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 Ã 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 Ã 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 â 2H₂ + O₂, 2.0 mol water will produce how many grams of O₂?

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

3.01 Ã 10²²

2.00

12.0 Ã 10²³

6.02 Ã 10²²

19.Suppose 2.43 g of magnesium is reacted with 3.20 g of oxygen: 2Mg + O₂ â 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 â Pbl₂ + NaNO₃

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 â 2CO₂

O₂

CO and O₂

CO₂

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 â 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 Ã 10⁴ kcal

C.53.1 kcal

D.5.31 Ã 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 Ã 10³ kcal

C.186 kcal

D.2.23 Ã 10³ kcal

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

A.201 kcal

B.2.41 Ã 10³ kcal

C.186 kcal

D.2.23 Ã 10³ kcal

golddinosaur326

WHICH OF THE FOLLOWING IS NOT AN ARRHENIUS BASE? KOH NH3 LiOH Sr(OH)2 Mg(OH)2 WHICH OF THE FOLLOWING IS A STRONG ACID IN AQUEOUS SOLUTION? HC2H3O2 HC1 HC1O2 H2S HC1O WHICH OF THE FOLLOWING REACTIONS IS NOT AN ACID-BASE REACTION? CaO + SiO2 rightarrow CaSiO3 CH3CHO + H2 rightarrow CH3CH2OH PO4^3- + H2O rightarrow HPO4^2- + OH- Na2O + SO3 rightarrow Na2SO4 BF3 + NH3 rightarrow F3BNH3 ALL OF THE FOLLOWING ARE OXIDATION-REDUCTION REACTIONS EXCEPT: H2(G) + F2 rightarrow 2HF(G) Ca(S) + H2(G) rightarrow CAH2(S) 2K(S) + 2H2O(L) rightarrow 2KOH(AQ) H2(G) 6Li(S) + N2(G) rightarrow 2Li3N(S) Mg3N2(S) + 6H2O(L) rightarrow 3Mg(OH)2(S) + 2NH3(G) WHICH OF THE FOLLOWING IS BEST DESCRIBED AS AN OXIDATION-REDUCTION REACTION? SO2(G) + H20(L) rightarrow H2SO3(AQ) 2C1(G) rightarrow C12(G) 3O2(G) rightarrow 2O3(G) 2NO2(G) rightarrow N2O4(G) SO2(G) + O2(G) rightarrow SO3 WHICH OF THE FOLLOWING REACTIONS INVOLVES NEITHER OXIDATION NOR REDUCTION? N2 + 3H2 rightarrow 2NH3 NH4NO2 rightarrow N2 + 2H2O Cu + 2Ag+ rightarrow Cu^2+ + 2Ag 2CrO4^2- + 2H+ rightarrow Cr2O7^2- + H20 C2H4 + H2 rightarrow C2H6 ASSIGN OXIDATION NUMBERS TO EACH ATOM IN NITROUS ACID. H = +1, N=+5, 0=-l H=+l, N=+5, O=-2 H=+l, N=+3, O=-l H=+l, N=+3, O=0 H=+l, N=+3, O=-2 FOR THE REACTION THAT OCCURS IN A LEAD STORAGE BATTERY, Pb(S) + Pb02(S) + 2H+(AQ) + 2HS04-(AQ) rightarrow 2PbSO4(S) + 2H20(L) THE OXIDIZING AGENT IS HSO4- PbSO4 Pb PbO2 H+ IN THE BALANCED EQUATION 3Na+ + 3OH- + P4 + 2H2O rightarrow 3Na+ + 3H2OP2- + PH3 WHAT IS THE REDUCING AGENT? OH- Na+ H2O P4 PH3 ALL OF THE FOLLOWING REACTIONS ARE CALLED COMBINATION REACTIONS EXCEPT BaO(S) + SO2(G) rightarrow BaSO3(S) C6H10(L) + Br2(L) rightarrow C6H10Br2(L) Br2(L) + H20(L) rightarrow HOBr(AQ) + HBr(AQ) CaC12(S) + 6H2O(L) rightarrow CaC12 * 6H2O(S) 3H2(G) + N2(G) rightarrow 2NH3(G) A 12.0 SAMPLE OF NaOH IS DISSOLVED IN WATER, AND THE SOLUTION IS DILUTED TO GIVE A FINAL VOLUME OF 1.80 L. THE MOLARITY OF THE FINAL SOLUTION IS 6.67 M 0.167 M 0.300 M 0.150 M 1.85 M HOW MANY GRAMS OF LITHIUM NITRATE, LiN03 (68.9 G/MOL), ARE REQUIRED TO PREPARE 511.5 mL OF A 0.101 M LiN03 SOLUTION? 0.000750 G 3.56 G 0.281 G 349 G 0.0735 G WHICH SUBSTANCE WOULD PRODUCE 2 MOL OF PARTICLES PER MOLE OF SOLUTE WHEN DISSOLVED IN WATER? NH4CH3COO CH2O CO2 SO2 A1(NO3)3 WHAT MASS OF H3PO4 (98 G/MOL) IS PRESENT IN 59.7 L OF A 0.0438 M SOLUTION OF H3P)4? 0.0267 G 0.00390 G 2.56 Times 10^2 G 1.34 Times 10^5 G 13.9 G WHICH OF THE FOLLOWING IS A CORRECT STATEMENT OF CHARLE'S LAW, V/T = k THE VOLUME OF A GAS VARIES PROPORTIONALLY WITH THE PRESSURE THE VOLUME OF A GAS SAMPLE VARIES DIRECTLY WITH THE ABSOLUTE TEMPERATURE ALL GAS SAMPLES OF THE SAME VOLUME OF STP CONTAIN THE SAME NUMBER OF ATOMS THE PRESSURE OF A GAS SAMPLE VARIES INVERSELY WITH THE VOLUME. ALL GAS SAMPLES OF THE SAME VOLUME AT STP CONTAIN THE SAME NUMBER OF MOLECULES. THE DENSITY OF A GAS IS 3.48 G/L AT STP. WHAT IS ITS MOLAR MASS? 115.7 G/MOL 104.7 G/MOL 6.4 G/MOL 22.4 G/MOL 78.0 G/MOL WHAT VOLUME OF AMMONIA GAS, MEASURED AT 455.9 MM HG AND 57.4 DEG C, IS REQUIRED TO PRODUCE 2.78 G OF AMMONIUM SULFATE ACCORDING TO THE FOLLOWING BALANCED CHEMICAL EQUATION? 2NH3(G) + H2SO4(AQ) rightarrow (NH4)2SO4(S) 0.0002233 L 0.000931 L 0.476 L 7.38 L 1.90 L CALCIUM NITRATE WILL REACT WITH AMMONIUM CHLORIDE AT SLIGHTLY ELEVATED TEMPERATURES, AS REPRESENTED IN THE EQUATION Ca(NO3)2(S) + 2NH4C1(S) rightarrow 2N2O(G) + CaC12(S) + 4H2O(G) WHAT IS THE MAXIMUM VOLUME OF N20 AT STP THAT COULD BE PRODUCED USING A 2.40-MOL SAMPLE OF EACH REACTANT? 6.55 Times 10^2 L 108 L 1.86 Times 10^-2 L 53.8 L 22.4 L WHAT IS THE PARTIAL PRESSURE OF CARBON DIOXIDE IN A CONTAINER THAT CONTAINS 7.64 MOL OF OXYGEN, 1.68 MOL OF NITROGEN, AND 1.42 MOL OF CARBON DIOXIDE WITH A TOTAL PRESSURE OF 529 MM HP? 376 MMHG 80.6 MMHG 82.7 MMHG 69.9 MMHG 529 MMHG A SAMPLE OF HYDROGEN IS COLLECTED BY WATER DISPLACEMENT AT 23.0 DEG C AND AN ATMOSPHERIC PRESSURE OF 735 MMHG. ITS VOLUME IS 568 ML. AFTER WATER VAPOR IS REMOVED, WHAT VOLUME WOULD THE HYDROGEN OCCUPY AT THE SAME CONDITIONS OF PRESSURE AND TEMPERATRE? (THE VAPOR PRESSURE OF WATER AT 23.0 DEG C IS 21 MMHG)509 mL 539 mL 552 mL 568 mL 585 mL

Practice problems for exam 2 ______________

Useful Information:

h=6.626Ã10-34JÂ·s.; c=3.0Ã108 m/sec; E=hï® ; E= hc , ï¬ = h/mv; 1J = 1 kg-m2/s2 ï¬

mass of electron = 9.11 Ã 10-28 g, ïE= q + w ; 1 cal = 4.184 Joules Please Show all Work

1. Which of the following substances have standard heats of formation that are equal to zero by definition (circle your answers): H2(g), H(g), O3(g), H2O(s), H2O(l), Hg(l), Hg(s), Hg(g).

2. Limestone stalactites are formed in the reaction: Ca2+(aq) + HCO3-(aq) ï CaCO3(s) + CO2(g) +

H2O(l)
If one mole of CaCO3 is produced at 298 K under one atmosphere of pressure, the reaction performs 590 calories of expansion work, pushing back the atmosphere as CO2 is formed. At the same time, 9310 calories of heat are absorbed from the environment. What is ïE in Kcal/mole for CaCO3.

3. What is the minimum wavelength of light in AÌ (1 AÌ = 10-8 cm) needed to provide enough energy per quantum to rupture the chemical bond in hydrogen iodide (HI). The bond dissociation energy of HI is 71.4 Kcal/mole.

4. Sketch the shape and orientation of the following types of orbitals: s, px, dxy, dz2, dx2-y2

5. Give the values of (n) , (l) and (ml) for each orbital in the 4p subshell.

6. Write the complete electron configuration for the following: Ti 2+_____________________________________ Cr_______________________________________

N______________________________________

7. Calculate the standard enthalpy of formation ( ï Ho) for diamond from graphite [i.e. C (graphite) ï C (diamond)] given that:

C (graphite) + O2 ï CO2 (g) ( ï Ho = -393.5 KJ/mole) C (diamond)] + O2 ï CO2 (g) ( ï Ho = -395.4 KJ/mole)

If 1.0g of graphite is converted to diamond, what is the energy change? Is this an endothermic or exothermic reaction?

8. An 160 pound astronaut on his way to Mars is buzzing along at 10,000 miles per hour. (a) Express his weight in grams (one pound = 454 grams) so that you can calculate the astronautâs wavelength (1mile/hour = 44.7 cm/sec)

(b) Suppose the astronaut detects outside his spacecraft a proton (m=1.7 x 10-24 g) from a âsolar windâ moving at exactly the spacecraft velocity. What is the proton wavelength is in AÌ (1 AÌ = 10-8 cm.

9. What is the maximum number of electrons that can occupy each of the following subshells? a) 3d_________________ b) 1s____________________ c) 2p ____________________

10. Identify the element represented by the following electronic configuration.

a) [Ne] 3s2____________________

b) What is the electron configuration for the first excited state of this atom.______________

11. Determine the number of valence electrons for each element.
(a) Br___________ (b) Na _________ (c) Sn __________

12. 175 g of Fe at 15.0oC is mixed with 225 g of H2O at 95.0oC. What is the final temperature of the mixture? The specific heats of iron= 0.448 J/g oC and water = 4.184 J/g oC). (keep in mind the following: heat gained + heat lost = 0 and q=mass x heat capacity x ïT)

13. (5 pts) Calculate values of ÎHrxn for the following reactions: CS2(g) + 3O2(g) ï® CO2(g) + 2SO2(g)

The heat of formation for the following substances is given in kJ/mol:

CS2 CO2 SO2 117.4 -393.51 -296.83

14. (6 pts) Use the electron configuration of Li and Be and determine which element has the greatest second ionization energy. Defend your answer.

15. Mark beside each of the following processes either âexoâ or âendoâ according to whether you think the process will release heat or absorb heat.

a. Ca(g) ï Ca(g)+2 + 2e-
b. I(g)+1e-ï I(g)-1
c. Ca(g)+2 + S(g)-2 ï CaS(s) d. I2(g)ï 2I(g)

( ) ( ) ( ) ( )

16. (6 pts) In each of the following pairs, which of the two species is larger?
a) O-2 or Na+ b) Ti+4 or Ti+2 c) B or C d) N or N-3

17. Write down the Lewis dot structure for the following (a) N_______________ (b) Ne________________

18. THE BORN HABER CYCLE: I may have a problem on the Born Haber cycle. Please check my lecture notes to see how to set up the process and then calculate the lattice energy from the various thermodynamic quantities such as in the NaCl example below;

ï H ï¯ f NaCl = -411KJ

Na(s) ï® Na(g) ï H =108KJ
1â2 Cl2 ï® Cl(g) ï H = 122KJ Ionization Energy of Na ï H = 496 KJ Electron affinity of Cl ï H = -349KJ

CH 104 Lecture Notes - Lecture 5: Molar Mass, Unified Atomic Mass Unit, Reagent

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