Chem Lab Final
What is the term for a gas that is collected over water? "dry" gas "wet" gas gaseous vapor water vapor
"wet" gas
A 0.200-g sample of unknown metal (X) is dropped into hydrochloric acid and releases 80.3 mL of hydrogen gas at STP. Using the Ideal Gas Law, the number of moles of the unknown is______, yielding a molar mass of______. Referring to the Periodic Table, the name of the unknown metal is________and symbol
.003581 55.85 Iron Fe
16 What is the mass of oxygen that reacted with magnesium given the following data? mass of a crucible and cover = 28.543 g mass crucible, cover, and magnesium = 28.742 g mass of crucible, cover, and magnesium oxide = 28.867 g -- Refer to Example Exercise 1 0.125 g 0.324 g 0.523 g 0.449 g 0.199 g
0.125 g
A 0.500-g sample of tin foil reacted with oxygen to give 0.635 g of product. Calculate the empirical formula of the tin oxide, reporting your answers to 3 significant figures. Do not use exponential notation or subscripts in your answers. a) The mass of oxygen used in the reaction is_______ g. b) The number of moles of tin____________ is moles and the number of moles of oxygen is _______moles. c) Using their ratio of number of moles, this yields an empirical formula of_____
0.135 0.00421 0.00844 SnO₂
A 1.000-g sample of cobalt metal reacted with sulfur powder to give 1.548 g of product. Reporting your answers to 3 significant figures. Do not use exponential notation or subscripts in your answers. a) The mass of sulfur used in the reaction is_____ g. b) The number of moles of cobalt is __________moles and the number of moles of sulfur is ________moles
0.548 0.0170 0.0171 CoS
17 What is the mass of sulfur that reacted with copper given the following data? mass of a crucible and cover = 30.663 g mass crucible, cover, and copper = 31.995 g mass of crucible, cover, and copper sulfide = 32.668 g 2.678 g 2.005 g 0.659 g 0.673 g 1.332 g
0.673 g
If 125 grams of magnesium sulfate heptahydrate is completely dehydrated, how many grams of anhydrous magnesium sulfate will remain?
100% - 51.172% H2O = 48.828% MgSO4 (125 g)(0.48828) = 61.0 g MgSO4
Select the coefficients needed to balance the chemical equation shown below. [ Select ] ["1", "4", "2", "3"] HNO3(aq) + [ Select ] ["3", "2", "1", "4"] Ba(OH)2(aq) --> 1 Ba(NO3)2(aq) + 2 H2O(l)
2 1 1 2
_____K(s) + [ Select ] ["2", "1", "4", "3"] Cl2(g) --> 2 KCl(s)
2 1 2
Provide the chemical formula for the white smoke produced in reaction A.1 from the data table:
2 MgO (s)
Provide the chemical formula for the strong odor produced in reaction A.2 from the data table:
2 SO (g)
15 How many moles are in 45.98 grams of sodium metal? 2 moles 4 moles 1 mole 22 moles
2 moles
A 0.0795 gram sample of magnesium metal reacts with hydrochloric acid to produce 88.5 mL of hydrogen gas at 25 oC and 766 mm Hg. From Table 1, the vapor pressure of water at 25 oC is_________mm. Referring to Example Exercise 1, the newly adjusted pressure is therefore,___________mm. Using the Combined gas Law, we can calculate the corrected (new) volume, which is_________ mL. In Liters, this value is_________ L. From their stoichiometric relationship of Mg and H2, the number of moles of H2 produced is__________mol. The molar volume of hydrogen is therefore,____________L/mol.
24.0 742 79.2 0.0792 3.27 x 10-3 24.2
14 What is the mass of one mole of magnesium metal? 12 g 24.1 mg 24.31 g 40.08 g
24.31 g
What are standard conditions of temperature and pressure for a gas? 0 °C and 1 mm Hg 273 °C and 760 mm Hg 0 K and 1 mm Hg 273 K and 760 mm Hg
273 K and 760 mm Hg
A 0.130-g sample of an unknown metal (X) reacted with hydrochloric acid according to the following chemical equation: 2 X (s) + 6 HCl (aq) ➝ 2 XCl3 (aq) + 3 H2 (g) The volume of hydrogen gas collected over water was 92.0 mL at 20 °C and 763 mm Hg. Referring to Example Exercise 2, the calculated atomic mass of the unknown metal is as_________g/mol, identifying the symbol of the metal from the periodic table as
52.0 Cr
A sample of hydrogen gas is collected over water at 25 °C and the vapor pressure of water at 25 °C is 24 mm Hg. If the barometer reading is 754 mm Hg, what is the partial pressure of the hydrogen gas? (Refer to Table 1).
730 mm Hg
A 0.200-g sample of cobalt metal reacted with hydrochloric acid according to the following balanced chemical equation:Co (s) + 2 HCl (aq) ➝ CoCl2 (aq) + H2 (g) The volume of hydrogen gas collected over water was 87.5 mL at 20 °C and a barometer reading of 763 mm Hg. Referring to Example Exercise 1, the adjusted volume of the H2 gas is_________ mL and the number of moles of H2 gas is_________mol. The calculated STP molar volume for hydrogen is___________L/mol.
79.9 0.00339 23.6
A solution of a substance dissolved in water.
Aqueous Solution
What causes the graduated cylinder to remain full after inverting it? Vapor pressure Atmospheric pressure Pressure exerted by the hydrogen gas Increased room temperature
Atmospheric pressure
Using the given formula of aluminum oxide, Al2O3, refer to the periodic table and predict the empirical formula for the oxide, B?O? B2O3 B3O3 B2O3 B3O2
B2O3
Write the formulas for the following compounds: a) barium chloride dihydrate _________________________________ b) magnesium sulfate heptahydrate ___________________________
BaCl2. 2H2O MgSO4 · 7H2O
Using the given formula of magnesium chloride, MgCl₂, refer to the periodic table and predict the empirical formula for the following halide: calcium chloride. CCl2 CaCl₂ CCl Ca₂Cl
CaCl₂
Which of the following laws states that the pressure exerted by a mixture of gases is equal to the sum of the partial pressures of each gas in the mixture? Boyle's law Charles's law Combined gas law Dalton's law
Dalton's law
Refer to the solubility flowcharts from the textbook for this question: CaCO3: Soluble or insoluble in H2O?
Insoluble
Refer to the solubility flowcharts from the textbook for this question: ZnS: Soluble or insoluble in H2O?
Insoluble
Calculate percent water for the following hydrates. MnSO4 . 4H2O
Mg: 24.31 g/molS: 32.07 g/mol4O: 64.00 g/mol7 H2O: 126.14 g/mol =246.52 g/mol 7 x 18.02 g/mol H2O = 126.14 g/mol mass of 7 H2O = 126.14 g/mol MgSO4•7H2O 246.52 g/mol x 100 = 51.17%
Open the Activity Series of Metals page in a different browser tab, so you can have the chart to answer these questions. Zn(s) + Al(NO3)3(aq) = Reaction or No Reaction?
No Reaction
Open the Activity Series of Metals page in a different browser tab, so you can have the chart to answer these questions. Zn(s) + Mg(NO3)2(aq) = Reaction or No Reaction?
No Reaction
A substance undergoing a chemical reaction.
Reactant
Open the Activity Series of Metals page in a different browser tab, so you can have the chart to answer these questions. Zn(s) + Cr(NO3)3(aq) = Reaction or No Reaction?
Reaction
Open the Activity Series of Metals page in a different browser tab, so you can have the chart to answer these questions. Zn(s) + Cu(NO3)2(aq) = Reaction or No Reaction?
Reaction
AC + B --> BC + A
Single replacement
Refer to the solubility flowcharts from the textbook for this question: Fe(C2H3O2)2: Soluble or insoluble in H2O?
Soluble
Refer to the solubility flowcharts from the textbook for this question: Mg(NO3)2: Soluble or insoluble in H2O?
Soluble
Refer to the solubility flowcharts from the textbook for this question: NH4Cl: Soluble or insoluble in H2O?
Soluble
Using the given formula of magnesium chloride, MgCl2, refer to the periodic table and predict the empirical formula for the following halide: strontium bromide. StBr StB₂ SrBr₂ Sr₂B
SrBr₂
Using the given formula of aluminum oxide, Al₂O₃, refer to the periodic table and predict the empirical formula for the oxides, Tl?O? TlO Tl₃O₂ Tl₂O³ Tl₂O₃
Tl₂O₃
Which of the following is an instrument for measuring the pressure exerted by gas molecules in the atmosphere? aerometer barometer pressure gauge thermometer
barometer
What is the term for rinsing a pipet or buret with a sample liquid or solution to avoid dilution by water on the inside surface of the glassware? condition wash dilute standardize
condition
What is the term for a substance that changes color according to the pH of a solution? endpoint acid base indicator
indicator
At the end point of a titration, the phenolphthalein indicator will cause the solution to turn: red yellow purple pink
pink
An insoluble solid substance produced from a reaction in aqueous solution.
precipitate
A substance resulting from a chemical reaction.
product
10 How can you tell when the magnesium metal has reacted completely? (Review Procedure A) a.)the metal changes to a gray-black residue the metal changes to a white powder adding distilled water produces ammonia gas small sparks are not observed when the crucible cover is lifted the crucible and cover glow red
small sparks are not observed when the crucible cover is lifted
The solution above a precipitate after insoluble particles separate.
supernatant
A + B --> AB
synthesis
What is the term for the pressure exerted by gaseous vapor above a liquid in a closed container when the rates of evaporation and condensation are equal? atmospheric pressure gas pressure partial pressure vapor pressure
vapor pressure
Select the coefficients needed to balance the chemical equation shown below. 1 ZnCO3(s) --> 1 ZnO(s) + 1 CO2(g)
1 1 1
____Sr(s) + [ Select ] ["1", "2", "4", "3"] H2O(l) --> 1 Sr(OH)2(aq) + [ Select ] ["3", "2", "1", "4"] H2(g)
1 2 1 1
Select the coefficients needed to balance the chemical equation shown below. [ Select ] ["3", "1", "4", "2"] Pb(NO3)2(aq) + [ Select ] ["3", "4", "1", "2"] LiCl(aq) --> [ Select ] ["3", "4", "2", "1"] PbCl2(s) + [ Select ] ["3", "1", "2", "4"] LiNO3(aq)
1 2 1 2
List the 4 observations that provide evidence for a chemical reaction.
1. change of temperature 2. a change of color 3. an emission of gas 4.the presence of an odor
A barometer reads 775 mm Hg. In three significant figures, express this atmospheric pressure in the following units:_______atm, or __________cm Hg, or______in Hg.
1.02 77.5 30.5
A 0.0795 gram sample of magnesium metal reacts with hydrochloric acid to produce 88.5 mL of hydrogen gas at 25 oC and 766 mm Hg. From Table 1, the vapor pressure of water at 25 oC is______mm Referring to Example Exercise 1, the newly adjusted pressure is therefore,______mm Using the Combined gas Law, we can calculate the corrected (new) volume, which is__________mL In Liters, this value is___________L. rom their stoichiometric relationship of Mg and H2, the number of moles of H2 produced is_______mol. The molar volume of hydrogen is therefore,________L/mol.
24.0 742 79.2 0.0792 3.27 x 10-3 24.2
Name the following compounds: a) FeCl3. 6 H2O ___________________________________________ b) CuSO4 . 5 H2O _________________________________________
A Iron(III) Chloride Hexahydrate B Copper(II) sulfate
Mercury chloride is a commercial fungicide. If the molar mass is 470 g/mol and the percent composition is 85.0% Hg and 15.0% Cl. a) The empirical formula of the fungicide is _________ b) Its molecular formula is _________ Refer to Examples in Lecture Slides
A. Base: 100 g => Hg = 85.0 g / 200.59 g/mol = 0.4235 mol Cl = 15.0 g / 35.45 g/mol = 0.4231 mol Hg = 0.4325 / 0.4231 = 1.00 Cl = 0.4231 / 0.4231 = 1.00 HgCl: 200.59 g/mol + 35.45 g/mol = 236.04 470 g/mol / 236.04 = 1.99 ≈ 2 HgCl
A relative order of metals arranged in a list according to their ability to undergo a chemical reaction.
Activity series
When distilled water is added to the crucible after the magnesium no longer sparks, this decomposes magnesium nitride and produces the gas, ___? Carbon dioxide
Ammonia
Using the given formula of magnesium chloride, MgCl2, refer to the periodic table and predict the empirical formula for the following halide: barium iodide. BI₂ BI Ba₂I BaI₂
BaI₂
AC + BD --> AD + BC
Double replacement
19 What is the empirical formula of iron oxide given the following data? mass of a crucible and cover = 27.500 g mass crucible, cover, and iron = 28.058 g mass of crucible, cover, and iron oxide = 28.218 g Fe2O3 FeO FeO2 Fe3O2 Fe2O
FeO
Using the given formula of aluminum oxide, Al2O3, refer to the periodic table and predict the empirical formula for the oxides, Ga?O? Ga2O3 Ga2O3 GA2O3
Ga2O3
Using the given formula of aluminum oxide, Al₂O₃, refer to the periodic table and predict the empirical formula for the oxides, Ga?O? Ga₂O₃ Ga²O³ GA₂O₃ Ga₃O³
Ga₂O₃
Refer to the solubility flowcharts from the textbook for this question: AgI: Soluble or insoluble in H2O?
Insoluble
Refer to the solubility flowcharts from the textbook for this question: AlPO4: Soluble or insoluble in H2O?
Insoluble
Refer to the solubility flowcharts from the textbook for this question: BaSO4: Soluble or insoluble in H2O?
Insoluble
Using the given formula of aluminum oxide, Al2O3, refer to the periodic table and predict the empirical formula for the oxides, In?O? InO In²O₃ In₂O₃ In²O³
In₂O₃
How is a hydrate different from other chemical compounds?
It has water molecules loosely attached to it. These water molecules can typically be removed through heating
Using the given formula of magnesium chloride, MgCl₂, refer to the periodic table and predict the empirical formula for the following halide: magnesium fluoride. MgF Mg₂F MgF2 MgF₂
MgF₂
18 A sample of magnesium ribbon is ignited in a crucible to form magnesium oxide. Determine the empirical formula of magnesium oxide from the following data: mass of crucible and cover + magnesium metal 33.741 g mass of the crucible and cover 33.500 g mass of crucible and cover + magnesium oxide 33.899 g Mg3O2 MgO Mg2O Mg2O3
MgO
12 The ___ of a substance is the mass of one mole of any substance, expressed in grams Mass Avogadro's number Molar Mass (MM) Volume
Molar Mass (MM)
Open the Activity Series of Metals page in a different browser tab, so you can have the chart to answer these questions. Zn(s) + Fe(NO3)2(aq) = Reaction or No Reaction?
Reaction
Open the Activity Series of Metals page in a different browser tab, so you can have the chart to answer these questions. Zn(s) + HNO3(aq) = Reaction or No Reaction?
Reaction
Refer to the solubility flowcharts from the textbook for this question: CuBr2: Soluble or insoluble in H2O?
Soluble
A technique that uses the relationship of quantities such as the mass or volume of a gas, in a chemical reaction according to the balanced chemical reaction is known as Mole concept Charles Law Stoichiometry STP
Stoichiometry
9. When, during the reaction of magnesium, should you place the cover on the crucible? a.)No need to cover the crucible during the reaction b.)Before turning on the burner c.)Immediately after turning on the burner d.)When the metal begins to spark
When the metal begins to spark
A 1.000-g sample of lead shot reacted with oxygen to give 1.077 g of product. Calculate the empirical formula of the lead oxide, reporting your answers to 3 significant figures. Do not use exponential notation or subscripts in your answers. a) The mass of oxygen used in the reaction is_____________g b) The number of moles of lead is_____________ moles and the number of moles of oxygen is _________moles. c)Using their ratio of number of moles, this yields an empirical formula of
a 0.0770 b 0.00483 c. PbO
21 Which of the following safety precautions is advisable? check the crucible for hairline cracks all of the above wear eye protection throughout the experiment avoid breathing sulfur dioxide gas avoid touching the hot crucible
all of the above
Which of the following is a source of serious experimental error? bubbles are not cleared from the tip of the buret the sodium hydroxide is not mixed thoroughly in the flask the buret is not conditioned all of these can cause serious experimental error
all of these can cause serious experimental error
In addition to wearing safety goggles, which of the following safety precautions is advisable? handle the buret carefully to avoid breakage avoid overfilling the buret all of these safety precautions are advisable avoid contact with NaOH
all of these safety precautions are advisable
20 Which of the following is a source of serious experimental error in determining the empirical formula of magnesium oxide? lifting the crucible cover to check the progress of reaction heating the crucible for more than 5 minutes cooling the crucible for more than 10 minutes allowing magnesium oxide to smoke excessively
allowing magnesium oxide to smoke excessively
What is the term for the pressure exerted by the air molecules in the Earth's atmosphere? air pressure atmospheric pressure gas pressure vapor pressure
atmospheric pressure
During a titration, what solution usually goes into the buret? indicator water base acid
base
When collecting a gas over water, how is the volume of the gas determined? by the volume of water remaining in the graduated cylinder by the volume of water required for complete reaction by the volume of acid required for complete reaction by the volume of water displaced
by the volume of water displaced
A substance that speeds up a chemical reaction.
catalyst
The indicator phenolphthalein changes the color of a solution based on pH. Phenolphthalein is______ in an acidic solution and [ Select ] in a basic solution.
clear pink
Which of the following laws states that the pressure exerted by a gas is inversely proportional to its volume and directly proportional to its Kelvin temperature? Boyle's law Charles's law combined gas law Dalton's law
combined gas law
AB --> A + B
decomp
Applying Charles's Law Concept. As a rubber balloon cools in a freezer, the volume decreases .
decreases
What is the term for the stage in an acid-base titration when the indicator changes color? endpoint stoichiometric point indicator point color point
endpoint
Applying Boyle's Law Concept. As a piston compresses air in a cylinder, the gas pressure increases .
increases
Applying Gay-Lussac's Law Concept. As an automobile tire rolls along the highway, the tire pressure increases .
increases
What is the term for the concentration expression that relates the mass of solute dissolved in each 100 grams of solution? parts per million (ppm) mass/mass percent (m/m %) molality (m) molarity (M)
mass/mass percent (m/m %)
What is the term for the volume occupied by 1 mole of any gas at STP? Avogadro's volume molar volume standard volume STP volume
molar volume
What is the term for the concentration expression that relates the moles of solute dissolved in each liter of solution? mass/mass percent (m/m %) parts per million (ppm) molality (m)
molarity (M)
13 A ____ is the amount of a substance that contains Avogadro's number of particles. Avogadro's number mole molar mass density
mole
A 0.500-g sample of chromium metal reacted with sulfur powder to give 0.963 g of product. a) The mass of sulfur that reacted is _____ b) The empirical formula of the chromium sulfide is _____
moles Cr = 0.500 g x 1 mol/ 52 g = 0.0096 moles Cr mass S = 0.963 g - 0.5 g = 0.463 g moles S = 0.463 g x 1 mol/32 g = 0.0145 moles S ratio of S/Cr = 0.0145/0.0096 = 1.5 Cr2S3
AD (acid) + BC (base) --> AC (salt) + BD (water)
neutralization
What is the term for a solution whose concentration has been established precisely (usually to three or four significant digits)? standard solution normal solution stock solution reference solution
standard solution
Which of the following is a source of serious experimental error? the buret is not conditioned the Erlenmeyer flasks are not dried before pipetting the vinegar samples two drops (not one drop) of phenolphthalein indicator are used
the buret is not conditioned
How can you tell when the endpoint in a titration is near? the pink color of the phenolphthalein indicator persists longer the sodium hydroxide drains from the buret more slowly the flask becomes warm the buret reads 50.00 mL
the pink color of the phenolphthalein indicator persists longer
In this experiment, how can you tell when the magnesium metal has reacted completely? the metal floats to the surface of the water the metal sinks to the bottom of the beaker the metal produces bubbles there are no more bubbles
there are no more bubbles
11 How can you tell when the copper has reacted completely and excess sulfur has burned off? (Review Procedure B) the crucible and cover glow red there is no trace of yellow sulfur the crucible contents change to a white powder the crucible contents change to a gray-black residue there is no trace of copper wire
there is no trace of yellow sulfur
What is the term for the procedure of delivering a measured volume of solution through a buret? QA or QC standardization titration conditioning
titration
