Exam 2 review
Calculate what volume of the following solutions is required to obtain 0.292 mol of each solute a) 0.262 M AlCl3 b) 3.97 M HCl
0.292X1/0.262 = 1.11 L 0.292X1/3.97 = 0.0736 L :)
Convert an energy of 0.733 kJ to units of calories.
0.733 kJ = 1.75 X10^2 cal 0.733X1000=733 joules 733/4.184=175 cal So then just 1.75 X10^2 :)
A chemical reaction was used to produce 3.67 moles of copper(II) bicarbonate, Cu(HCO3)2. What mass of copper(II) bicarbonate was produced?
678.95 (find molar mass of compound, here it is 185 then do 185X3.67 = 678.95 and double check by 678.95/185= 3.67)
A student was synthesizing aspirin in the laboratory. Using the amount of limiting reactant, she calculated the mass of aspirin that should form as 11.07 g. When she weighed her aspirin product on the balance, its mass was 7.57 g. Calculate the percent yield for this synthesis.
68.4% 7.57/11.07X100 = 68.4 % yield=actual yield/theoretical yieldX100
The balanced equation for the combustion of butane, C4H10, is 2 C4H10(g) + 13 O2(g) → 8 CO2(g) + 10 H2O(g) Calculate the moles of CO2 produced when 3.27 moles of C4H10 are allowed to react with 12.67 moles of O2
7.79 mol 3.27X13/2 = 21.255 12.67X2/13 = 1.949 12.67X8/13 = 7.79
Nitrogen monoxide reacts with oxygen according to the following reaction: 2NO(g) + O2(g) → 2NO2(g) If 12 moles of nitrogen monoxide are combined with 10 moles of oxygen, how many moles of NO2 should form?
12 moles ;)
The heat change that accompanies the formation of 1.00 mol of carbon dioxide from its elements is −393.7 kJ/mol. What heat change accompanies the formation of 0.558 mol CO2?
Heat change= -220 kJ 0.558X-393.7/1 = -220
What is the percent composition of Na3PO4?
Na: 42.1 P: 18.9 O: 39 Firstly find the atomic mass of each Na: 69, P:31, O: 64 then find the atomic mass of the total so here it is 164. 69/164X100 = 42.1 31/164X100 = 18.9 64/164X100 = 39
Calculate the moles and the mass of solute in 189.1 mL of 0.469 M CaCl2
moles of solute: 0.0887 (189.1X0.001X0.469) mass of solute in grams: 9.84 (0.0887X110) (110 is the mass of CaCl2) :)
When solid ammonium carbonate is heated, it decomposes to form ammonia gas, carbon dioxide gas, and water vapor, so that the solid completely disappears. Which of the following is the complete, balanced equation for this reaction?
(NH4)2CO3(s) → 2NH3(g) + CO2(g) + H2O(g) Just count the # of atoms of each element on both sides and see which answer has the same # of each on both sides hence, "BALANCED" ;)
If you wish to prepare a 1.10 M solution of NaNO3, to what volume (in liters) would you have to dilute 25.4 ml of 2.12 M NaNO3?
0.0490 L :) Firstly you want to turn your 25.4 ml into L by /1000 so that would be 0.0254 L. (2.12X0.0254)/1.10 = 0.0490 L
If 50.0 mL of 0.235 M NaCl solution is diluted to 200.0 mL, what is the concentration of the diluted solution?
0.0588 M (50)(0.235)/200 :)
Aluminum reacts with chlorine gas according to the following equation shown below. How many moles of Cl2 are required to react with 0.059 mol of Al? 2 Al(s) + 3 Cl2(g) → 2 AlCl3(s)
0.089 0.059X3/2 = 0.089 mol Cl2
Calculate the molarity of 163 grams of sucrose, C12H22O11, in 4.90 liters of solution.
0.097 molar mass: 342 moles: 0.476 (163X1/342) liter: 4.90 molarity: 0.476/4.90 = 0.097
Sodium hydroxide reacts with aluminum and water to produce hydrogen gas: 2 Al(s) + 2 NaOH(aq) + 6 H2O(l) → 2 NaAl(OH)4(aq) + 3 H2(g) What mass of hydrogen gas would be formed from a reaction of 2.35 g Al and 4.22 g NaOH in water?
0.264 g 2.35X1/26.98X3/2X2.016/1 = 0.264
Calculate the molarity of 171 grams of sucrose, C12H22O11, in 1.80 liters of solution.
0.277 First you want to find the molar mass of the compound here it is 342. (C12: 144, H22: 22, O11: 176) (atomic mass of each) MOLARITY=MOLES/LITER moles: 0.5 (171X1/342) liter: 1.80 molarity: 0.5/1.80 = 0.277
How many formula units are in 1.1 mol of CuSO4?
1.1X6.02214X10^23 = 6.62X10^23 CuSO4 formula units
In order to prepare a 0.0500 M NaOH solution, to what volume would you dilute 25.0 mL of 2.50 M NaOH?
1.25 L :) same as above 25.0 ml -> 0.025 L (2.50X0.025)/0.0500 = 1.25 L
How many SO2 molecules are in 2.57 mol of SO2? How many sulfur atoms and oxygen atoms are there?
2.57X6.02214X10^23 = 1.55X10^24 SO2molecules Since there is only 1 S atom = 1.55X10^24 S atoms Since there are 2 O atoms, 1.55X2 so= 3.10X10^24 O atoms. (6.02214X10^23 is Avogrados #)
Convert an energy of 643 cal to units of joules.
2692.2 joules X4.187 per cal :))
Magnesium metal reacts with gaseous oxygen in a combination reaction. Write a balanced equation to describe this reaction. Include states of matter.
2Mg (s) + O2 (g) ----> 2MgO (s) lol idkkk sorry :(
Decomposition of NI3 produces nitrogen gas and iodine. How many grams of the reactant would be required to react completely to give 3.50 g of the iodine?
3.63 g Before we attempt to solve this problem, we need to construct a balanced chemical equation for the decomposition of NI3. 2 NI3(s) → N2(g) + 3 I2(s) Molar masses: I2 (253.8g/mol), NI3 (394.7g/mol) 3.50X1/253.8X2/3X394.7/1 = 3.63
When the reddish-brown mercury(II) oxide (HgO) is heated, it decomposes to its elements, liquid mercury metal and oxygen gas. If 4.17 g HgO is decomposed to Hg, calculate the mass of the pure Hg metal produced. 2 HgO(s) ---heat---> 2Hg (l) + O2 (g)
3.86 g Hg 4.17X1/216.6X2/2X200.6/1 = 3.86 g Hg
How much heat has to be added to 429 g of iron at 25.0°C to raise the temperature of the iron to 250.0°C? (The specific heat of iron is 0.448 J/g ·°C.)
4.32X10^4 same as above:))
A 5.05 g sample of quartz (SiO2) contains 2.36 g of silicon. What are the percentages of silicon and oxygen in quartz?
46.7% Si and 53.3% O 2.36/5.05X100 = 46.7% 5.05-2.36=2.69 2.69/5.05X100 = 53.3%
A 3.75-g sample of limestone (CaCO3) contains 1.80 g of oxygen and 0.450 g of carbon. What is the percent O and the percent C in limestone?
48% - O 12% - C 1.80/3.75X100 = 48% 0.450/3.75X100 = 12%
Ethanol, used in alcoholic beverages, can be produced by fermentation of sucrose. The balanced equation for the fermentation process is shown below. What mass of ethanol (C2H5OH) would be produced when 9.90 g sucrose reacts by this process? C12H22O11 (s) + H2O(l) → 4 C2H5OH(l) + 4 CO2 (g)
5.33 g ethanol 9.90X1/342.3X4/1X46.07/1 = 5.33
How much heat has to be added to 568 g of copper at 22.3°C to raise the temperature of the copper to 49.8°C? (The specific heat of copper is 0.377 J/g·°C.)
5.89 X 10^3 J 49.8-22.3=27.5 (568)(0.377)(27.5)=5888.74 So then just 5.89X10^3 :)
How many sulfur atoms are in 5.8 mol of SO2?
5.8X6.02214X10^23 = 3.49X10^24 atoms (Since there is only one S atom in SO2 then its the same as if you were looking for SO2)
How much heat energy would be needed to raise the temperature of a 15.0 g sample of iron [C = 0.448 J/(g°C)] from 22.0°C to 100.0°C?
524 J 100-22=78 15X0.448X78=524
Iron metal reacts with hydrochloric acid as follows: 2Fe(s) + 6HCl(aq) → 2FeCl3(aq) + 3H2(g) If 35.6 g of iron react with excess HCl, and 98.6 g of FeCl3 are collected, what is the percent yield of FeCl3?
95.4%
If 1.0 mol of Mg is mixed with 2.0 mol of Br2, and 0.97 mol of MgBr2 is obtained, what is the percent yield for the reaction? Mg(s) + Br2(l) → MgBr2(s)
97% 0.97/1.0X100 = 97%
The decomposition reaction of calcium carbonate is represented by the following balanced equation: CaCO3(s) --heat--> CaO(s) + CO2(g) After a 15.8−g sample of calcium carbonate was heated in an open container to cause decomposition, the mass of the remaining solid was determined to be 9.10 g. The reaction may or may not have gone to completion, so the solid could contain unreacted CaCO3. Calculate the percent yield of CO2.
97% 15.8-9.10 = 6.7 15.8X1/100.09X1/1X44.01/1 = 6.95 6.7/6.95X100 = 97%
If 75.0 J of heat energy is added to 25.0 g samples of different metals. Given their specific heat values, rank the metals in order from least to greatest final temperature.
Al < Cr < Cu < Ag < Au
Complete and balance each of the following single-displacement reactions. Include physical states
Al(s) + CuSO4(aq)→ Al2(SO4)3(aq) + 3Cu (s) Cs(s) + H2O(l)→ 2CsOH (aq) + H2 (g)
Which of the following are combustion reactions?
CH4 (g) + O2 (g) ---> CO2 (g) + H2O (l)
Which of the following have identical empirical formulas
C2H4 and C3H6 have identical emperical formulas of CH2
A compound with the empirical formula CH2O has a molar mass of approximately 90 g/mol. Write its molecular formula.
C3H6O3 first find the weight of the emp formula compound here it is 30 (12+2+16) then compare it with the molar mass of the molecular formula which here it says its 90. 30 to 90 would be X3 so X3 every atom! :)
Molecular formula to Empirical formula examples
C6H4Cl2 -> C3H2Cl C6H5Cl -> same thing since you can't have a ratio with 5 or the one Cl. N2O5 -> same thing since you cant have ratio with 5. N2O4 -> NO2 H2C2O4 -> HCO2 CH3CO2H -> COH2, this one needed some cleaning lol just combine all the atoms together and then see what it is divisible by so on this one there was two O's and two C's and four H's. so the slice it in half since they are all divisible by two! :)
Write the empirical formula of the compound with the following composition: 63.15% C, 5.30% H, 31.55% O
C8H8O3 FIRSTLY divide by each elements atomic mass so 63.15/12= 5.2625 moles, 5.30/1= 5.3 moles, 31.55/16=1.9718 moles THEN divide all the answers by the smallest answer which here it is 1.9718. So 5.2625/1.9718= 2.66, 5.3/1.9718= 2.68, and 1.9718/1.9718=1. THEN you end up with C-2.66, H-2.68, O-1 FINALLY you want to X by a whole number that is close so here it would be 3.
Which of the following ionic compounds would be expected to be soluble in water?
CuCl2 and AgNO3
Convert grams of Fe2O3 to grams of Fe
Fe2O3 (s) + 3CO (g) --> 2Fe (s) + 3CO2 (g) Steps: 1) g Fe2O3 2) X1molFe2O3/159.7g Fe2O3 3) mol Fe2O3 4) X2mol Fe/1mol Fe2O3 5) mol Fe 6) X55.85g Fe/1mol Fe 7) g of Fe
For each, decide whether it represents a chemical reaction or a physical change.
H2O(s) →H2O(l) - physical change CO2(g) + H2O(l) →H2CO3(aq) - chemical change HOCN(g) →HCNO(g) - chemical change
Which of the following is an acid/base reaction?
HBr + KOH ---> KBr + H2O
Calculate the molar mass of each of the following compounds: Hg2Cl2 and Cl2O5
Hg2Cl2: 470 g/mol Cl2O5: 150 g/mol (look up atomic mass of each element and X by however many atoms there are, then add up) Ex. Cl2O5: AM of Cl is 35 and AM of O is 16 so 35X2= 70 and OX5= 80, so 70+80= 150.
Soluble: LiOH, (NH4)2S, Ca(C2H3O2)2, (NH4)2SO4, Na2CO3, NaNO3, KCl
Insoluble: Fe(OH)2, PbS, PbBr2, PbF2, CaCO3, AgCl, BaSO4, Ag2SO4
Identify the spectator ions in the following reaction: H2SO4(aq) + 2KOH(aq) → K2SO4(aq) + 2H2O(l)
K+ (aq) and SO4^2- (aq)
If 45.0 mL of a 6.00 M HCl solution are diluted to a final volume of 0.250 L, what is the final concentration?
M2 = 1.08 M FIRST change the "0.250 L" to mL by X1000 = 250 (45.0)(6.00)/250 = 1.08 M
Which of the following is a single replacement reaction?
Mg + 2HNO₃ → Mg(NO₃)₂ + H₂
Which of the following molecules have an empirical formula that is different from their molecular formula?
Molecular formula: whole #'s in a compound kind of like the main formula Empirical formula: RATIO of the molecular formula EX. H2O2 mole form can be HO as an empirical form since it is just sliced in two but still equal. As well as N2O4 mole form can be NO2 emp form since we just sliced in half. EX. of mole form that can NOT be turned into emp form: HCO2H bc the only atom that has two is O so you can not slice in half the H or the C.
A gaseous compound has the empirical formula NO2. If its molar mass is approximately 92 g/mol, what is its molecular formula?
N2O4 atomic weight= 46 (14+32) molar mass of mole formula is 92. which is X2 So X2 every atom. :)
Identify the spectator ion(s) in the following reaction: Zn(s) + Cu(NO3)2(aq) → Cu(s) + Zn(NO3)2(aq)
NO3- (aq) only
Which of the following is a precipitation reactions?
Pb(NO3)2 (aq) + K2S (aq) ---> KNO3 (aq) + PbS (s)
Aqueous solutions of sodium sulfate and lead(II) nitrate are mixed and a white solid forms. What is the formula of the solid?
PbSO4(s)
When heated, platinum(IV) chloride undergoes a decomposition reaction. Write a balanced chemical equation to describe this reaction. Include states of matter.
PtCl4 (s) ----> Pt (s) +2Cl2 (g) uh I guess just look up the formula for platinum chloride and then just stretch it out lol idk good luck :p
Calculate the number of moles in 149.3 g of each of the following compounds
SO2: 2.330 moles Na2SO4: 1.051 moles BaSO4: 0.640 moles KAl(SO4)2: 0.578 moles (149.3/molar mass) to find molar mass just get the atomic mass of each element in the compound and add them up. EX. KAl(SO4)2: K mass is 39, Al mass is 27, there are two atoms of S so mass is 64, there is eight atoms of O so mass is 128. Add them up and you get 258 now do 149.3/258 = 0.578
Identify the solute and solvent in this solution containing calcium chloride and water.
Solute: CaCl2 Solvent: H2O
How many mL of a 2.50 M NaOH solution are required to make 525 mL of a 0.150 M NaOH solution?
V1 = 31.5 mL (0.150)(525)/2.50 = 31.5 M1V1=M2V2
Write a balanced equation to describe any precipitation reaction that should occur when the following substances are mixed. If no reaction occurs, then answer 1 for the coefficients and write NR for the products.
a) 1MgSO4(aq) +1BaCl2(aq)→MgCl2(aq) + BaSO4 (s) b) 1K2SO4(aq) + 1MgCl2(aq) --> NR c) 1MgCl2(aq) + 1Pb(NO3)2(aq) → Mg(NO3)2 (aq) + PbCl2 (s)
Suppose you want to convert iron ore to a specific amount of pure iron using the following reaction: Fe3O4(s) + 4CO(g) → 3Fe(s) + 4CO2(g) a) What mole ratio would you use in the following equation to determine the number of moles of CO needed to react with a known amount of Fe3O4? b) If you add more than enough CO so that all the Fe3O4 reacts, what mole ratio would you use in the following equation to determine the moles of CO2 produced? c) Suppose you know the number of moles of Fe product formed and you want to know the number of moles of CO that reacted. What mole ratio would you use in the following equation?
a) 4 mol , CO/ 1 mol, Fe3O4 b) 4 mol, CO2/ 1 mol, Fe3O4 c) 4 mol, CO/ 3 mol, Fe
The balanced equation for the decomposition of ammonium nitrate is: 2NH4NO3(s) → 2N2(g) + O2(g) + 4H2O(g) a) Select the mole ratios that relate moles of each product to the reactant NH4NO3. b) How many moles of each product would form if 1.00 mol of NH4NO3 reacts? c) How many moles of each product would form if 9.82 mol of NH4NO3 react?
a) All 6 ways b) N2- 1.00 mol, O2- 0.500 mol, H2O- 2.00 mol Moles of N2= 1.00X2/2, Moles of O2= 1.00X1/2, Moles of H2O= 1.00X4/2. look at the equation to see how many of each! c) N2- 9.82 mol. O2- 4.91 mol. H2O- 19.6 mol. 9.82X2/2, 9.82X1/2, 9.82X4/2
The balanced equation for the reaction of aluminum metal and chlorine gas is 2Al(s) + 3Cl2(g) → 2AlCl3(s) Assume that 0.79 g Al is mixed with 0.47 g Cl2. a) what is the limiting reactant? b) What is the maximum amount of AlCl3, in grams, that can be produced?
a) Cl2 b) 0.59 g AlCl3 0.47X1/70.90X2/3X133.3/1 = 0.59
Which of the following single-displacement reactions will actually occur if the indicated reactants are mixed?
a) Ni(s) + FeCl2(aq)→NiCl2(aq) + Fe(s) - no reaction b) 2Al(s) + 3NiCl2(aq)→2AlCl3(aq) + 3Ni(s) - yes reaction c) Fe(s) + CuCl(aq)→FeCl2(aq) + Cu(s) - yes reaction d) 3Sn(s) + 2AlCl3(aq)→3SnCl2(aq) + 2Al(s) - no reaction
a) 2 elements -> 1 compound b) 1 element and 1 compound -> 1 element and 1 compound c) 1 compound -> 2 elements d) 1 compound -> 1 element and 1 compound e) 2 compounds -> 2 compounds f) 2 compounds -> 1 compound
a) combination b) single-displacement c) decomposition d) decomposition e) double-displacement f) combination
2 NaHCO3(s) ----heat----> Na2CO3(s) + CO2(g) + H2O(g)
decomposition I knew it was decomp since the C's and O's were stretched out into more places. So just check and see the places of the elements :)
The following reaction releases 2800 kJ of heat for each mole of C6H12O6 that reacts. C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(l) This reaction is
exothermic and has a negative value of q.
The following reaction absorbs 393 kJ of heat for each mole of CO2 that reacts. CO2(g) → C(s) + O2(g) This reaction
is endothermic and has a positive value of q
If the same amount of heat is added to 25.0 g of each of these metals, all at the same initial temperature, which metal will have the highest final temperature?
lead
A marble is added to 51.0 g of water. The initial temperature of the water is 25.0°C. The final temperature of the water and the marble is 22.2°C. What is the heat change of the marble? (The specific heat of water is 4.184 J/g·°C.)
marble = 6X10^2 J 22.2-25=-2.8 51X4.184X-2.8=-597.47 which rounds to -6 so its 6X10^2
