| Assessment Questions: 58 results |
Thermochemistry : SystemSurrExoEndo (4 Variations)
Sulfuric acid is added to water in a beaker and the resulting solution is much warmer than either the water or acid was initially.
Identify the following items as being part of the system or the surroundings, and indicate whether the process is exothermic or endothermic.
Calorimetry / Thermochemistry
|
Thermochemistry : BondEnergies (10 Variations)
Use  to determine which of the following requires the most energy.
Calorimetry / Thermochemistry
|
Thermochemistry : FlaskTemp (6 Variations)
If 200. J of thermal energy was added to both flasks, which of the following would happen?
Calorimetry / Thermochemistry
|
Thermochemistry : GeneralEnergy (10 Variations)
Which of the following statements about energy is NOT true?
Calorimetry / Thermochemistry
|
Thermochemistry : ThermalEnergy (2 Variations)
The sketch below shows two identical flasks with different volumes of water at the same temperature. Which of the following is true?
Calorimetry / Thermochemistry
|
Thermochemistry : HeatTransfers (10 Variations)
A red-hot piece of lead is dropped into water. Which of the following statements are true? (Assume that there are no energy transfers between anything except the lead and the water.)
Calorimetry / Thermochemistry
|
Thermochemistry : BombCalorimeter (4 Variations)
Stearic acid (CH3(CH2)16CO2H) is a fatty acid, the part of fat that stores most of the energy. 1.00 g of stearic acid was burned in a bomb calorimeter. The bomb had a heat capacity of 652 J/oC and a 500. g water reservoir. If the temperature rose from 25.0 to 39.3 oC, how much heat was released when the stearic acid was burned?
Calorimetry / Thermochemistry |
Chemometrics
|
Thermochemistry : CalcHStateChange (4 Variations)
Calculate the enthalpy change when 100. g of ice at 0.0 oC is heated to liquid water at 50.0oC. (The heat of fusion for water is 333 J/g.)
Calorimetry / Thermochemistry |
Chemometrics
|
Thermochemistry : CoffeeCupCalorimeter (2 Variations)
A block of copper is heated to {x} °C and then is dropped into a coffee cup calorimeter containing {y} g of water at 25.0 °C. The final temperature of the system is 45.1 °C. What is the mass of the copper block to the nearest gram? (Assume all heat is transferred to the water). Write your answer in the box, and do NOT include units.
Specific heat capacity of copper = 0.383 J/(g*°C)
Specific heat capacity of water = 4.18 J/(g*°C)
Calorimetry / Thermochemistry |
Chemometrics
|
Thermochemistry : FuelAmpWattHeat (4 Variations)
Gasoline has an enthalpy of combustion of approximately 24000 kJ/gallon. When gasoline burns in an automobile engine, approximately 30% of the energy released is used to produce mechanical work. The remainder is lost as heat transfer to the engine's cooling system and eventually the atmosphere. As a start on estimating how much heat transfer is required, calculate what mass of water could be heated from 25 to 100oC by the combustion of 1.0 gallon of gasoline in an automobile.
Calorimetry / Thermochemistry |
Chemometrics
|
Thermochemistry : HeatCapacityGraph (6 Variations)
Consider the graph above. Which of these substances has the highest specific heat capacity?
Calorimetry / Thermochemistry |
Heat Capacity
|
Thermochemistry : HeatCapacityLiq (4 Variations)
100 g of water (c=4.184 J/g.oC), 100 g of ethanol (c=2.46 J/g.oC), 100 g of carbon tetrachloride (c=0.861 J/g.oC), and 100 g of ethylene glycol (c=2.42 J/g.oC) at 50oC were each placed into a separate coffee cup calorimeter and the temperature recorded. The temperature of the surroundings was 20oC. After one hour the temperature of which substance would have changed by the largest amount? Assume that the rate of heat transfer from the coffee cup to the surroundings was the same in each case.
Calorimetry / Thermochemistry |
Heat Capacity
|
Thermochemistry : CalcHBondEnergy (14 Variations)
Use the bond energies given in to estimate the  Ho for the reaction given below:
hint: both carbon dioxide and molecular oxygen have double bonds
Calorimetry / Thermochemistry |
Chemometrics
|
Thermochemistry : CalcHCombustion (6 Variations)
Using the thermodynamic data given in  , determine the enthalpy change for the combustion of ethane to produce carbon dioxide and water vapor. 2C2H6(g) + 7O2(g) 4CO2(g) + 6 H2O(g)
Calorimetry / Thermochemistry |
Chemometrics
|
Thermochemistry : EnthalpyEnergy (10 Variations)
2SO2(g) + O2(g)2SO3(g)
Horxn = -197.78 kJ
How much energy is transferred when 96.6 g of SO2 reacts to form SO3?
Calorimetry / Thermochemistry |
Chemometrics
|
Bonding : EnergyBreakAllBonds (10 Variations)
Use the bond energies given in to determine the total energy needed to break all of the bonds in C3H6. (Do not use ring structures.)
Covalent Bonding |
Calorimetry / Thermochemistry
|
Thermochemistry : HeatCapacitySolLiq (4 Variations)
The Table below lists the specific heat capacities of several metals and liquids.
| Substance |
Specific Heat Capacity
J/(g.oC) |
Substance |
Specific Heat Capacity
J/(g.oC) |
| Al |
0.902 |
H2O |
4.18 |
| Fe |
0.451 |
C2H5OH |
2.46 |
| Cu |
0.383 |
CCl4 |
0.861 |
| Au |
0.128 |
CCl2F2 |
0.598 |
In an experiment, 50 g of a metal was heated to 100oC and placed in 200 g of a liquid at 25oC. Which of the following combinations of metal and liquid will produce the largest temperature increase in the liquid? (Assume that there is no transfer of energy to the surroundings.)
Calorimetry / Thermochemistry |
Heat Capacity
|
Thermochemistry : CalcHHessLaw (8 Variations)
The industrial process for making sulfuric acid has three steps. Using the data given, calculate the enthalpy change for the overall reaction for the process (the equation is given below).2S(s) + 3O2(g) + 2H2O(l)2H2SO4(l)
Data:
| S(s) + O2(g) SO2(g)
| Hrxn = -296.83 kJ
|
| 2SO3(g)O2(g) + 2SO2(g)
| Hrxn = -198.2 kJ
|
| SO3(g) + H2O(l)H2SO4(l)
| Hrxn = -227.72 kJ
|
Calorimetry / Thermochemistry |
Chemometrics
|
Thermochemistry : MassFromCalorimetry (2 Variations)
The table below lists the specific heat capacities of several metals and liquids. | Substance | Specific Heat Capacity
J/(g.oC) | Substance | Specific Heat Capacity
J/(g.oC) | | Al | 0.902 | H2O | 4.18 | | Fe | 0.451 | C2H5 OH | 2.46 | | Cu | 0.383 | CCl4 | 0.861 | | Au | 0.128 | CCl2F2 | 0.598 |
In an experiment a block of aluminum was heated to 100oC and placed in 200 g of water at 25oC. If the final temperature of the system is 43oC, and no heat transfer to the surroundings occurred, what is the mass of the aluminum block?
Calorimetry / Thermochemistry |
Chemometrics
|
Thermochemistry : CalcMolarEnthalpy (5 Variations)
White phosphorus, P4, ignites in air to produce heat, light, and P4O10 according to the following reaction. P4(s) + 5O2(g) P4O10(s) If 67.2 g of P4 is burned,1620 kJ of energy is evolved. What is the molar enthalpy of combustion of P4 if the process was carried out under constant pressure?
Calorimetry / Thermochemistry |
Chemometrics
|
Thermochemistry : ConvertEnergyUnits (4 Variations)
The label on a granola bar says it provides 120 Calories. How many kilojoules of energy will this bar provide if it is completely metabolized?
Calorimetry / Thermochemistry |
Nomenclature / Units / Symbols
|
Thermochemistry : PhaseChangeEnthalpy (10 Variations)
A solid melts to a liquid. Which of the following statements are true? (Assume constant pressure and a flexible container.)
Calorimetry / Thermochemistry |
Phases / Phase Transitions / Diagrams
|
Thermochemistry : PhaseChanges (8 Variations)
Steam at 100oC is condensed by an ice-water mixture at 0oC. Assuming that there is still ice present when the process is over, how much ice will be melted if 10.0 g of steam is condensed? The following may be useful:
enthalpy of vaporization of water = 40.7 kJ/mol; enthalpy of fusion of water = 6.07 kJ/mol; specific heat capacity of water = 4.184 J/g•K.
Calorimetry / Thermochemistry |
Phases / Phase Transitions / Diagrams
|
Intermolecular_Forces__Liquids_and_Solids : PhaseEnergyChanges (6 Variations)
When a liquid is transformed into its vapor at constant temperature,
Phases / Phase Transitions / Diagrams |
Calorimetry / Thermochemistry
|
Stoichiometry : GramMoleProblem (9 Variations)
Which sample contains the largest number of nitrogen atoms?
Stoichiometry
|
Stoichiometry : StoicNeeds (10 Variations)
You have a known mass of a compound X and react it to form compound Y. What is the minimum information you need to find the mass of Y produced?
Stoichiometry
|
Atoms,_Molecules_and_Ions : MassInAlloy (10 Variations)
Gold is alloyed with other metals to make it less malleable. 10 karat gold is an alloy that is 41.7% gold. How much pure gold is in a 20. gram 10 karat gold ring?
Stoichiometry
|
Stoichiometry : LimitingReagent (8 Variations)
The synthesis of urea by Frederich W??hler in 1825 began the decline of the idea that "organic" chemicals could only be made by living organisms as part of their biological processes. AgOCN(aq) + NH4Cl(aq) AgCl(s) + NH2CONH2(aq) If you perform this reaction and collect the following table of data, in which trial(s) is AgOCN clearly the limiting reactant?
| Trial
|
AgOCN used
|
NH4Cl
|
AgCl produced
|
| 1
|
20.4 mL
|
5.3 mL
|
2.4 g
|
| 2
|
20.3 mL
|
10.4 mL
|
4.3 g
|
| 3
|
20.6 mL
|
15.4 mL
|
6.2 g
|
| 4
|
20.5 mL
|
20.6 mL
|
8.2 g
|
| 5
|
20.4 mL
|
25.2 mL
|
10.2 g
|
| 6
|
20.3 mL
|
30.4 mL
|
10.3 g
|
The mL of AgOCN and NH4Cl are the initial amounts used, the mass of AgCl is how much was recovered from the reaction. (Hint: You do not need to do any calculations to answer this question.)
Stoichiometry
|
Gases : VolGasReactInTorch (10 Variations)
Oxyacetylene torches used in high-temperature welding use a combination of oxygen and acetylene. The combustion of acetylene (C2H2) occurs in these torches. What volume of oxygen is needed to react with 250 mL of acetylene?
Gases |
Stoichiometry
|
Stoichiometry : CalcPercentYield (8 Variations)
When copper is heated in air, copper(II) oxide is formed. In a given experiment, 1.50 g copper was heated to yield 1.76 g copper(II) oxide. What is the percent yield?
Stoichiometry |
Chemometrics
|
Stoichiometry : CalcWeightPercent (8 Variations)
What is the weight percent of oxygen in LiHCO3?
Stoichiometry |
Chemometrics
|
Stoichiometry : EmpirFormulaFromRxn (10 Variations)
When one mole of a diatomic gas, Y2(g), reacts with one mole of hydrogen gas, neither gas is left over. What is the empirical formula of the compound formed?
Stoichiometry |
Reactions
|
Stoichiometry : GeneralMassMole (4 Variations)
10.0 g of nitrogen monoxide is reacted with 10.0 g of oxygen to form nitrogen dioxide. Which of the following statements is true?
Stoichiometry |
Reactions
|
Stoichiometry : RxnNanoPics (4 Variations)
The following diagram shows a compound reacting to form products. Which equation best describes the stoichiometry of the reaction shown in the diagram?
Stoichiometry |
Reactions
|
Stoichiometry : BalanceRxn (14 Variations)
The reaction of methane with oxygen has the following unbalanced equationCH4(g) + O2(g) CO2(g) + H2O(l) The coefficient for oxygen in the balanced equation is ...
Stoichiometry |
Reactions
|
Stoichiometry : DiagramRxnProds (6 Variations)
According to the law of conservation of matter, which of the following diagrams represents possible products of the following reaction?
A2 + 2B2
Stoichiometry |
Reactions
|
Stoichiometry : CalcTheorYield (10 Variations)
If you react 6.2g of phosphine with 8.30g of oxygen, what is the theoretical yield of phosphorous pentaoxide?
4PH3 + 8O2 P4O10 + 6H2O
Stoichiometry |
Chemometrics
|
Stoichiometry : DeterMolesInRxn (4 Variations)
The reaction of zinc with aqueous hydrochloric acid has the following unbalanced equation Zn(s) + HCl(aq) ZnCl2(aq) + H2(g) When 0.1 moles of zinc is reacted with 0.1 moles of hydrochloric acid ...
Stoichiometry |
Reactions
|
Stoichiometry : TheorYieldDeviation (10 Variations)
You reacted a known amount of phosphorous triiodide with excess water and determined that the percent yield of phosphoric acid was less than 100%, which of the following statements could explain why?
PI3 + 3H2O H3PO3 + 3HI
Stoichiometry |
Reactions
|
Stoichiometry : CalcWtPercent (6 Variations)
A standard dose of antacid as a calcium supplement is two tablets. The active ingredient in many of these tablets is calcium carbonate. One tablet, having a weight of 1.415 g, is reacted with excess HCl(aq) to produce 0.22 g CO2. What is the weight percent of calcium in this tablet? CaCO3(s) + 2HCl(aq)CaCl2(aq) + H2O(l) + CO2(g)
Stoichiometry |
Chemometrics
|
Stoichiometry : CalcPercentPurity (4 Variations)
To test the purity of calcium sulfate, you dissolve a 4.56g sample in water and add oxalic acid to precipitate out calcium oxalate. If 3.45g of precipitate forms, what is the percent purity of the calcium sulfate?
CaSO4(aq) + H2C2O4(aq) CaC2O4(s) + H2SO4(aq)
Stoichiometry |
Chemometrics
|
Solutions : RelativeConc (4 Variations)
What are the relative concentrations of the ions in 0.10 M aqueous sulfuric acid?
Solutions / Solvents |
Stoichiometry
|
Stoichiometry : AtomsAndGrams (10 Variations)
How many moles of atoms does a 500. g bar of gold contain?
Stoichiometry |
Nomenclature / Units / Symbols
|
Stoichiometry : CombustionAnalysis (10 Variations)
While working in the lab, you find a bottle of white powder labeled
"analgesic compound #5". Since the original investigator neglected
to record the identity of the substance, you decide to perform a
combustion analysis to identify the compound. You have a 65.7 g
sample that when burned produces 182 g CO2 and 51.7 g
H2O. What is the formula of this compound? (The compound
only consists of C,H, and O.)
Stoichiometry |
Molecular Properties / Structure
|
Stoichiometry : ExplainYldError (4 Variations)
Your TA gives you an aqueous solution containing an unknown quantity of AgNO3(aq) and an unknown quantity of Mg(NO3)2(aq). You are asked to determine the molarity of Ag+ in the solution. You add HCl(aq) to your unknown to precipitate the silver as AgCl(s), then filter out the precipitate, dry it, weigh it, and calculate the concentration of silver ion. However, your TA tells you that your calculated value of [Ag+(aq)] is lower than the actual value. Which of the following could account for your answer being too low? There may be more than one correct answer.
Stoichiometry |
Reactions |
Chemometrics
|
Stoichiometry : FormulaFromComp (8 Variations)
Lactic acid is the substance that makes your muscles burn when you've been exercising hard. Lactic acid is composed of 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by weight. If it has a molar mass of 90 g/mol, what is its molecular formula?
Stoichiometry |
Molecular Properties / Structure
|
Stoichiometry : PrecipYield (3 Variations)
In a laboratory experiment to determine accurately the amount of barium in solution, aqueous sulfuric acid was added to the solution to precipitate barium sulfate, which was then filtered and weighed. In this experiment it is MOST important that ...
Stoichiometry |
Reactions |
Chemometrics
|
Bonding : DetermineStructure (8 Variations)
H
A substance is analyzed and found to contain 57.10% carbon, 4.80% hydrogen and 38.06% oxygen by weight. Its molecular weight is determined to be 126.11 g/mol. Which of the structures shown are possible structures for the substance?
Molecular Properties / Structure |
Stoichiometry
|
Atoms,_Molecules_and_Ions : AtomicRatio (10 Variations)
Which compound(s) contain the most nitrogen atoms per molecule or formula unit?
Molecular Properties / Structure |
Stoichiometry
|
Atoms,_Molecules_and_Ions : BinaryMolcFromImage (8 Variations)
Which of the following binary compounds could the figure below best represent? 
Molecular Properties / Structure |
Stoichiometry
|
Atoms,_Molecules_and_Ions : IonicFormula (10 Variations)
Which pair of ions will form a compound of formula M2X?
Molecular Properties / Structure |
Stoichiometry
|
Atoms,_Molecules_and_Ions : CalcMolarMass (8 Variations)
What is the molar mass of potassium phosphate,
K3PO4?
Enter the numeric value very carefully below, rounding to one decimal place only. Do not put the units in, but think about what the
units are!
Molecular Properties / Structure |
Stoichiometry
|
Stoichiometry : GivenYieldCalcStMat (4 Variations)
Calcium oxide and water are produced by heating calcium hydroxide. If the reaction has an expected yield of 60%, how much calcium hydroxide should be reacted to produce 115g of calcium oxide?
Ca(OH)2 CaO + H2O
Stoichiometry |
Reactions |
Chemometrics
|
Stoichiometry : MolsO2ToReactFuel (10 Variations)
Butane can be used as a fuel. How many moles of oxygen are needed to completely react with 3.0 moles of butane?
The unbalanced reaction equation is given below:
C4H10(g) + O2(g) CO2(g) + H2O(g)
Stoichiometry |
Reactions |
Chemometrics
|
Stoichiometry : RxnMolsProduced (8 Variations)
Given the following balanced chemical reaction:
4A + 3B2 2A2B3
If 12 moles of A are reacted with excess B2, how many moles of A2B3 will be produced?
Very carefully enter the number below.
Stoichiometry |
Reactions |
Chemometrics
|
Stoichiometry : GivenMassCalcStMat (10 Variations)
Aspirin is a common analgesic. If you want to produce 250. mg of aspirin (C9H8O4) from the reaction of C7H6O3 and C4H6O3, what is the minimum amount of C7H6O3 that is needed? 2C7H6O3(s) + C4H6O3(l) 2C9H8O4(s) + H2O(l)
Stoichiometry |
Reactions |
Chemometrics
|
Stoichiometry : RxnTable (10 Variations)
Iron reacts with oxygen to form iron(III) oxide according to the following reaction.
4Fe(s) + 3O2(g)2Fe2O3(s)
|
Fe(s)
|
O2(g)
|
Fe2O3(s)
|
| Initial Amount
|
-
|
-
|
-
|
| Change
|
-
|
-
|
-
|
| End Amount
|
-
|
-
|
-
|
Complete the reaction table for a reaction mixture containing 12.0 moles of iron and 10.0 moles of oxygen, and select the true statement(s) from following list.
Stoichiometry |
Reactions |
Chemometrics
|
Stoichiometry : SolnStoich (4 Variations)
You are working in a forensic lab and are given a blood sample from a suspected drunk driver and asked to determine the person's blood alcohol level. The legal limit is 0.08% by mass in most states. You use the following reaction in your determination, assuming only the ethanol (C2H5OH) in the blood sample will react with the dichromate.
16H+(aq) + 2Cr2O72-(aq) + C2H5OH(l) 4Cr3+(aq) + 11H2(l) + 2CO2(g)
If 14.6 mL of 0.10 M K2Cr2O7 are needed to react completely with 28 g of blood, what is the blood alcohol level of the driver?
Stoichiometry |
Reactions |
Chemometrics
|
