CHEM 1212K Lab Final

In a precipitation reaction, what symbol identifies the precipitate product?

(s)

A certain type of light has a wavelength of 658 nm. What is this value in meters?

0.000000658

Consider the reversible dissolution of lead(II) chloride. PbCl2(s)−⇀↽−Pb2+(aq)+2Cl−(aq) Suppose you add 0.2265 g of PbCl2(s) to 50.0 mL of water. When the solution reaches equilibrium, you find that the concentration of Pb2+(aq) is 0.0159 M and the concentration of Cl−(aq) is 0.0318 M. What is the value of the equilibrium constant, Kc, for the dissolution of PbCl2 ?

0.0000161

Consider the reversible dissolution of lead(II) chloride. PbCl2(s)−⇀↽−Pb2+(aq)+2Cl−(aq) Suppose you add 0.2482 g of PbCl2(s) to 50.0 mL of water. When the solution reaches equilibrium, you find that the concentration of Pb2+(aq) is 0.0159 M and the concentration of Cl−(aq) is 0.0318 M. What is the value of the equilibrium constant, Kc, for the dissolution of PbCl2 ?

0.0000161

The molar solubility of Ca(OH)2 was experimentally determined to be 0.019 M. Based on this value, what is the Ksp of Ca(OH)2 ?

0.000027

Suppose, in an experiment to determine the amount of sodium hypochlorite in bleach, you titrated a 23.57 mL sample of 0.0100 M KIO3 with a solution of Na2S2O3 of unknown concentration. The endpoint was observed to occur at 13.66 mL . How many moles of KIO3 were titrated?

0.0002357

Suppose in an experiment to determine the amount of sodium hypochlorite in bleach, 0.000529 mol KIO3 were titrated with an unknown solution of Na2S2O3 and the endpoint was reached after 17.80 mL . How many moles of Na2S2O3 did this require?

0.003174

Suppose in an experiment to determine the amount of sodium hypochlorite in bleach, 0.0000157 mol KIO3 were titrated with an unknown solution of Na2S2O3 and the endpoint was reached after 17.39 mL . What is the concentration of the Na2S2O3 solution, in M?

0.00542

A 25.0 mL sample of a saturated Ca(OH)2 solution is titrated with 0.023 M HCl , and the equivalence point is reached after 38.0 mL of titrant are dispensed. Based on this data, what is the concentration (M) of Ca(OH)2 ?

0.017

A 25.0 mL sample of a saturated Ca(OH)2 solution is titrated with 0.026 M HCl , and the equivalence point is reached after 37.9 mL of titrant are dispensed. Based on this data, what is the concentration (M) of the hydroxide ion?

0.039

How many kilometers is 4481.9 cm?

0.044819

Glucose (molar mass=180.16 g/mol) is a simple, soluble sugar. Glucose solutions are used to treat patients with low blood sugar. Suppose you prepare a glucose solution using the described procedure. Step 1: Dissolve 290.8 g of glucose in enough water to make 500.0 mL of solution. Step 2: Transfer 16.3 mL of the solution to a new flask and add enough water to make 250.0 mL of dilute solution. What is the concentration (in M) of the glucose solution at the end of the procedure?

0.21 Molar

Calculate the concentration (in M) of acetate ion in a buffer solution made from 2.00 mL of 0.50 M acetic acid and 8.00 mL of 0.50 M sodium acetate .

0.4

Determine whether or not each combination of substances can be used to create a buffer.

1 M Na2HPO4, 1 M NaH2PO4; Buffer 0.1 M HNO2, 0.05 M NaOH; Buffer 0.4 M KOH, 0.2 M NaOH; Not a buffer 0.1 M HCl, 0.1 M KCl; Not a buffer 0.05 M HNO2, 0.05 M NaNO2; Buffer

Knowing that one day is 24 hours, how many days is 67.1 hours?

2.8

Suppose you are working with a NaOH stock solution but you need a solution with a lower concentration for your experiment. Calculate the volume (in mL) of the 1.459 M stock NaOH solution needed to prepare 250.0 mL of 0.1316 M dilute NaOH solution.

22.55 mL NaOH

If a photon has a wavelength of 592.9 nm, what is the energy of the photon (in J)?

3.35e-19

A formic acid buffer solution contains 0.18 M HCOOH and 0.13 M HCOO− . The pKa of formic acid is 3.75. What is the pH of the buffer?

3.61

Aspirin can be prepared from salicylic acid ( C7H6O3 ), which has a molar mass of 138.12 g/mol, and acetic anhydride ( C4H6O3 ), which has a molar mass of 102.04 g/mol. The density of acetic anhydride is 1.082 g/mL. C7H6O3+C4H6O3⟶C9H8O4+C2H4O2 What is the theoretical yield, in grams, of aspirin ( C9H8O4 ), which has a molar mass of 180.15 g/mol, possible when reacting 3.16 g of salicylic acid with 3.53 mL of acetic anhydride?

4.12

Consider the balanced reversible reaction of acetic acid with ethanol. When you react acetic acid with ethanol, the equilibrium concentration of acetic acid is . What is the equilibrium concentration (M) of ethyl acetate?

4.6

Using the procedure in Determination of an Equilibrium Constant, a student combines equimolar amounts of acetic acid and ethanol to react as shown by the following equation. acetic acid + ethanol ⇌ ethyl acetate + water To determine the initial concentration of acetic acid, 1.00 mL of the resulting mixture was titrated with 0.2005 M NaOH , requiring 27.55 mL . What is the molarity of the acetic acid?

5.52

Changing gloves often will minimize the spread of chemicals. To properly remove gloves, first, ____, and then, ____. Then insert ____ between the interior edge of the second glove and the skin, and remove the second glove.

Changing gloves often will minimize the spread of chemicals. To properly remove gloves, first, grasp the exterior of one glove with a gloved hand, and then, peel off the first glove . Then insert a bare finger between the interior edge of the second glove and the skin, and remove the second glove.

Match each definition to the appropriate term.

Difference of the enthalpy (of a system) minus the product of the entropy and absolute temperature; Gibbs free energy Solution in which no more solute can be dissolved in the solvent; Saturated solution The extent of randomness in a system; Entropy The condition that a reaction takes place without outside help; Spontaneity Sum of the internal energy plus the product of the pressure and volume for a reaction; Enthalpy

Suppose you analyze a 36.1 g sample of bleach and determine that there are 2.39 g of sodium hypochlorite present. What is the percent of sodium hypochlorite in the bleach sample?

6.62

Identify the value of each number presented in scientific notation.

7.32×106; 7320000 4.65×103; 4650 4.65×10−3; 0.00465 7.32×10−4; 0.000732

Suppose you are studying the Ksp of KClO3 , which has a molar mass of 122.5 g/mol, at multiple temperatures. You dissolve 4.00 g of KClO3 in 12 mL of water at 85 oC and cool the solution. At 74 oC, a solid begins to appear. What is the Ksp of KClO3 at 74 oC?

7.4

Sulfuric acid, H2SO4 , is an important industrial chemical, typically synthesized in a multi-step process. What is the percent yield if a batch of H2SO4 has a theoretical yield of 3.9 kg, and 2.8 kg are obtained at the end of the process?

72

Identify correctly formatted scientific notation. Select one or more:

8×106 4.532×10−9 6.1×1012

An ammonia buffer solution contains 0.25 M NH4+ and 0.22 M NH3 . The pKa of ammonium is 9.24. What is the pH of the buffer?

9.18

In the Determination of an Equilibrium Constant lab, you will react acetic acid with ethanol in the presence of sulfuric acid until equilibrium is established. Then, you will titrate the equilibrium mixture with NaOH to determine the acetic acid concentration. Suppose you determine that the added sulfuric acid requires 2.97 mL of NaOH to be neutralized in a blank solution. The equilibrium mixture requires 12.92 mL of NaOH to reach the endpoint. What volume of NaOH should you use to calculate the acetic acid concentration at equilibrium?

9.95 mL

What information does not need to be included a chemical waste label?

A description of the experiment the chemicals were used for

Identify the following silver salts as soluble or insoluble in water.

AgI; Insoluble AgNO3; Soluble AgCl; Insoluble

What are the best practices for safely handling waste in the lab?

Always wear appropriate Personal Protective Equipment. Check labels or instructions before any disposal.

Identify the types of information that are necessary to communicate with emergency responders.

Any chemicals involved in an incident How the incident happened Any other hazards present in the lab

What is the best safety approach when working with unknown chemical substances?

Assume that the substance is hazardous. Always wear appropriate PPE and take steps to prevent contact.

Determine whether the stopcock should be completely open, partially open, or completely closed for each activity involved with titration.

At the beginning of a titration; Completely open Conditioning the buret with titrant; Completely closed Close to the calculated endpoint of a titration; Partially open Filling the buret with titrant; Completely closed

The equilibria studied in the lab procedure include which two reactants?

Fe3+ [CoCl4]2−

Gamma rays and visible light are both ____ but gamma rays have ____ than visible light.

Gamma rays and visible light are both electromagnetic radiation but gamma rays have more energy than visible light.

Determine whether each description corresponds to an endothermic reaction or an exothermic reaction.

Heat is a reactant in the reaction; Endothermic The reaction mixture feels warm from the outside; Exothermic The reaction mixture feels cool from the outside; Endothermic Heat is a product in the reaction; Exothermic

Fill in the table by predicting the sign of ΔG and whether or not the process is spontaneous.

High T + + - yes Low T + + + no High T - - + no Low T - - - yes All T + - + no All T - + - yes

Which electromagnetic wave corresponds to each description?

Highest energy; B Shortest wavelength; B Second Highest energy; A Lowest frequency; C

What information is necessary to review in order to be considered familiar with the Safety Data Sheet (SDS) of a substance?

Identification and description of substance Hazard warnings Personal protection and first aid recommendations Handling, storage, and reactivity information

If you drop or break glassware in lab, first _____. Then, ____. Finally, place all that material into the ____.

If you drop or break glassware in lab, first get thick gloves or dustpan . Then, carefully collect all the broken glassware. Finally, place all that material into the broken glass container.

Where should glassware be stored after it is cleaned?

In a drying oven, or designated locations such as drawers or buret racks

Review the Safety Data Sheet (SDS) (click the SDS icon below) for hydrogen peroxide, then identify the best course of action for each type of chemical exposure.

In case of eye contact; Rinse with water for 15 minutes. If inhaled; Move person to fresh air. If swallowed; Rinse mouth with water. In case of skin contact; Take off any contaminated clothing and rinse thoroughly

Consider the two reactions of iron ions, one with thiocyanate ( SCN− ) ions and one with chloride ( Cl− ) ions. Fe3++SCN−−⇀↽−FeSCN2+ Fe3++4Cl−−⇀↽−FeCl4− If you create an equilibrium mixture from Fe3+ and SCN− ions, adding Cl− ions will shift the iron-thiocyanate equilibrium to the reactant side because it removes iron from the iron-thiocyanate equilibrium mixture.

shift the iron-thiocyanate equilibrium to the reactant side; it removes iron from the iron-thiocyanate equilibrium mixture

Identify the correct equation for the equilibrium constant Ka for the weak acid dissociation of acetic acid. HC2H3O2(aq)+H2O(l)−⇀↽−H3O+(aq)+C2H3O2−(aq)

Ka=[H3O+][C2H3O2−]/[HC2H3O2]

Fill in the expression for the equilibrium constant Kc for the reaction given. A+2B⟷2C+D

Kc=C^2D/AB^2

Identify the correct equation for the equilibrium constant Kc for the reaction given. Cu(s)+2AgNO3(aq)−⇀↽−Cu(NO3)2(aq)+2Ag(s)

Kc=[Cu(NO3)2]/[AgNO3]2

All lab participants must remain prepared to use safety equipment in case of emergency. Identify the components of effective preparation.

Knowing what safety equipment is available; Understanding where the safety equipment is located; Being familiar with how safety equipment is used

If x represents the molar solubility of Ba3(PO4)2 , what is the correct equation for the Ksp ?

Ksp=(3x)^3(2x)^2

If x represents the molar solubility of Ca(OH)2 , what is the correct equation for the Ksp ?

Ksp=4x^3

When taking a measurement with a pH meter, keep the instrument in the storage solution until it is needed. Rinse the pH meter with deionized water and gently pat dry. Place the meter in the sample solution, and record the measurement when the pH stabilizes.

storage solution; deionized water; stabilizes

The extent of a compound's dissolving is based on the thermodynamic quantities of enthalpy and entropy. The enthalpy of dissolving depends on the strength of attraction between the ions in the solid state and between the ions and the solvent. The entropy of dissolving is usually thermodynamically favored because the ions have more available arrangements when dissolved.

strength of attraction; the solvent; favored; more available arrangements

To identify a halide, you can react a solution with chlorine water in the presence of mineral oil. If the unknown halide is a stronger reducing agent than chlorine, the halide will be oxidized to its elemental form which would change the color of the mineral oil layer.

stronger; its elemental form; mineral oil

To determine the enthalpy and entropy of dissolving a compound, you need to measure the Ksp at multiple temperatures. Then, plot ln(Ksp) vs. 1/T. The slope of the plotted line relates to the enthalpy of dissolving and the intercept of the plotted line relates to the entropy of dissolving.

temperatures; 1/T; enthalpy; entropy

When preparing a solution in a cuvette, make sure to handle the cuvette by the textured sides and avoid touching the smooth sides. Then, wipe down the cuvette before placing it in the spectrophotometer.

textured sides; smooth sides; wipe down

According to Le Châtelier's Principle, heat applied to an exothermic reaction will shift the reaction towards the reactants. Heat applied to an endothermic reaction will shift the reaction towards the products.

the reactants; the products

In the Kinetics of an Iodine Clock Reaction procedure, the initial rate is calculated by multiplying the initial concentration of the thiosulfate ion by half, and dividing by the elapsed time as measured with a a stopwatch.

the thiosulfate ion; a stopwatch

Arrange the colors of the visible spectrum in order from highest to lowest energy.

violet - Highest energy blue green yellow orange red - Lowest energy

Based on the data, choose the correct exponents to complete the rate law. rate=k[NO]x[H2]y

x=1; y=1

Identify the precautions to take with exits in the lab.

Locate the exits prior to the start of lab. Do not block a door with an EXIT sign.

When taking pH measurements of solutions, why is it important to stir thoroughly after adding each reagent?

Mixing helps ensure that the measured pH is reflective of the entire solution.

While setting up a beaker to boil a solution on a hot plate, you notice that the stirring is erratic and unstable. What should you do to stabilize the stirring solution?

Move the beaker to the center of the hot plate. Turn down the stirring speed.

Move to the safety shower if you spill hazardous chemicals on your________. Stand under the shower and ____ the lever. Remove clothing and continue flushing the area for _____.

Move to the safety shower if you spill hazardous chemicals on your skin or clothing. Stand under the shower and pull the lever. Remove clothing and continue flushing the area for 15 minutes.

Most laboratory chemical spills are cleaned up in a similar manner, but acid and base spills require an extra step. What is this extra step?

Neutralize the spill before cleaning it up.

Determine whether each description relates to wavelength or frequency.

Often measured in units such as Hertz (Hz); Frequency Often measured in units such as nanometers (nm); Wavelength A measure of cycles per unit time; Frequency Increases as energy decreases; Wavelength A measure of distance; Wavelength Increases as energy increases; Frequency

Identify the medical applications of aspirin.

Pain killer Fever reducer Anti-inflammatory agent Anti-coagulant

When any reversible reaction is at equilibrium, what conditions are necessarily true?

Reactants and products are both present in the reaction mixture. The rate of the forward reaction equals the rate of the reverse reaction. The amounts of reactants and products has stopped changing.

NFPA diamond

Red=Flammability, Yellow=Reactivity, Blue=Health, White=Special Precautions, 1 is lowest hazard, 4 is extremely hazardous

What is the first step for response to an emergency situation?

Remain calm and quiet, gather information, and assess the situation.

What should you do every time before you leave the lab?

Remove your gloves. Wash your hands. Remove your labcoat, if you are wearing one.

How should spill cleaning materials be discarded?

Seal in a labeled plastic bag, then place in the solid waste container.

Which of the following forms precipitates with most halogens?

Silver nitrate

What visible signs indicate a precipitation reaction when two solutions are mixed?

Solid settling out in the test tube A hazy or cloudy appearance

Concentration data is commonly monitored during a reaction to determine the order with respect to a reactant. Consider the types of observations listed, and determine which order is likely for that reactant. Assume all other factors are held constant.

The reaction rate is constant regardless of the amount of reactant in solution; zero order The reaction rate increases in direct proportion to the concentration of the reactant in solution; first order An increase in the concentration of the reactant in solution causes the reaction rate to increase exponentially; second order

At what times should a pH electrode be submerged in a solution?

When being stored in a storage cabinet When not being used between measurements When monitoring a reaction in a beaker

Determine when you should remove your goggles in the lab room.

When everyone in the room is done handling any chemicals or glassware

When heating a solution to boiling on a hot plate, start by ____. Then, turn the heat to ____ to start. If necessary, ____ after waiting about ten minutes without seeing boiling.

When heating a solution to boiling on a hot plate, start by starting and stabilizing the stir function. Then, turn the heat to a medium heat setting to start. If necessary, turn up the heat setting after waiting about ten minutes without seeing boiling.

When should you start a new chemical waste container in the lab?

When the contents of the current container are a couple inches below the brim of the container

If the dissolution of borax in water is spontaneous, is the change in enthalpy positive or negative - or are both signs possible? Both signs are possible. Why do you predict this? The sign of the enthalpy changedepends on the temperature.

both signs are possible; the sign of the enthalpy chage depends on the temperature

Determine where to dispose of each type of waste.

broken flask; Box lined with puncture resistant bag syringe tips; Sharps container unused solid reagent; Solid waste container titrant solution; Nalgene bottle with cap

Aspirin is usually packaged with buffering agents to reduce its acidity and the related stomach irritation.

buffering agents; acidity; stomach irritation

To find the order of a reaction with respect to one reactant, you will monitor the change in rate of reaction as the concentration of the reactant is changed.

change in rate of reaction; concentration; the reactant

Identify the items needed to run a spectrophotometry experiment.

cuvette spectrophotometer sample solutions blank solution

Iron(III) chloride can be used to assess the purity of aspirin synthesized from salicylic acid. Iron(III) chloride does not react with aspirin because the reaction requires a phenolic functional group which is present in salicylic acid but not aspirin.

does not; a phenolic functional group; salicyclic acid but not aspirin

Determine which items of personal protective equipment (PPE) you will likely use in a general chemistry lab.

goggles; gloves; lab coat

Suppose the reaction of chlorine water with a halide solution produces a halogen, X2, and a salt, NaCl. In the presence of mineral oil, the halogen will dissolve in the oil and the salt will remain in the aqueous layer.

halogen; salt

Identify the description that applies to the substance represented by each NFPA diamond.

has a flash point below room temperature (COR in white square); moderately unstable or reactive (blue=3,red=0,yellow=2); stable, has health risks but no special hazards (blue=2,red=3,yellow=0); oxidizer, not flammable (OX in white square)

When borax is dissolved in water, do you expect the standard entropy of the system to increase or decrease? increase Why do you predict this? Entropy generally increases when solids are dissolved. Will the sign of ΔSsys be positive or negative? positive

increase; entropy generally increases when solids are dissolved; positive

When determining the amount of an oxidant present by titration, you can use iodine and starch as an indicator. First, the oxidant, like hypochlorite, oxidizes iodide ion into neutral iodine . When starch and iodine are both present, the solution is blue-black. During the titration, the titrant, like thiosulfate, reduces the neutral iodine into iodide ion. When the iodine has completely reacted at the endpoint of the titration, the solution should become clear.

iodide ion into neutral iodine; blue-black; neutral iodine into iodide ion; clear

Identify the equipment best suited for extinguishing each type of fire.

large fire on floor; fire extinguisher small benchtop fire; overturned beaker clothing fire; fire blanket

Determine the best way to deal with each of the following items that may dangle into the way during lab work.

long necklaces; Remove loose bracelets; Remove long earrings; Remove flowy sleeves; Tie back or secure long hair; Tie back or secure

The solubility of PbF2 is expected to be lower in a solution of NaF than in pure water. This is because the NaF solution contains fluoride ions that inhibit further dissociation of PbF2 into Pb2+ and F− .

lower; fluoride ions; inhibit

Select the missing words to complete the definition of buffer capacity. Buffer capacity is the moles of acid or base a buffer can handle before pushing the pH outside of the buffer range.

moles; pH

Consider the equilibrium describing the endothermic dissolution of a solid in water. Zn(OH)2(s)−⇀↽−Zn2+(aq)+2OH−(aq) If you have a saturated solution at equilibrium, what changes could you make to increase the solubility of the compound?

Increase the temperature Add HCl(aq)

What should you do every time you are about to heat glassware on a hot plate?

Inspect the hot plate for frayed cords Check that there are no cracks in the glassware Ensure that the glassware is designed for heating

Which warning about iodine is accurate?

Iodine can stain the body and other surfaces.

In the reactionMg + 2HCl → MgCl2 + H2Mg is oxidized and H is reduced.

oxidized; reduced

Use the Ka values for weak acids to identify the best components for preparing buffer solutions with the given pH values.

pH=3.9; formic acid/sodium formate pH=5.0; acetic acid/sodium acetate pH=1.9; phosphoric acid/monosodium phosphate

To run a thin layer chromatography experiment with a chemical substance, begin by marking a horizontal line near the bottom of a TLC plate with pencil. Place a small spot of the substance onto the line. For the mobile phase, add a small amount of solvent at the bottom of a TLC chamber. Place the plate in, then cover the chamber. Once the mobile phase approaches the top of the plate, remove the plate and mark the solvent line. Note the position of the spots and calculate Rf values if needed.

pencil; small; solvent; cover; solvent

When using the method of initial rates for a kinetic study, the reaction is performed several times. One reactant concentration is kept constant, and the other varies.

several times; varies

A saturated AgCl solution was analyzed and found to contain 1.25 x 10-5 M Ag+ ions. Use this value to calculate the Ksp of AgCl .

1.56E-10

Knowing that one day is 24 hours and one hour is 60 minutes, how many minutes are in 7.0 days?

10000

A 250 mL sample of saturated AgOH solution was titrated with HCl , and the endpoint was reached after 2.60 mL of 0.0136 M HCl was dispensed. Based on this titration, what is the Ksp of AgOH ?

2.0E-8

Aspirin can be prepared from salicylic acid ( C7H6O3 ), which has a molar mass of 138.12 g/mol, and acetic anhydride ( C4H6O3 ), which has a molar mass of 102.04 g/mol. The density of acetic anhydride is 1.082 g/mL. C7H6O3+C4H6O3⟶C9H8O4+C2H4O2 What is the yield, in grams, of aspirin ( C9H8O4 ), which has a molar mass of 180.15 g/mol, possible when reacting 2.04 g of salicylic acid with 1.23 mL of acetic anhydride?

2.35

Suppose you mix NaCl and AgNO3 solutions according to the given equation. NaCl(aq)+AgNO3(aq)⟶AgCl(s)+NaNO3(aq) What evidence of a reaction do you expect to see?

A precipitate should form.

Identify the chromatography term that corresponds to each definition.

A value that quantifies the distance traveled by a substance relative to the distance traveled by the solvent; Rf The substance to which the sample is bound at the start of an experiment; stationary phase The substance that carries the components of a mixture; mobile phase A method used to separate components of a mixture; chromatography

Using the letters on the image, identify each component of the liquid waste set-up.

A; Funnel B; Primary container C; Waste label D; Secondary container

Suppose you are going to perform a TLC experiment, which materials will you use to prepare the TLC development chamber?

Beaker Filter paper Watch glass

Determine when to put on disposable gloves for work in the lab.

Before handling any glassware or chemicals for the experiment

When should lab participants look at the Safety Data Sheet (SDS) of a substance?

Before using the substance

When using a pH meter to monitor a stirring reaction mixture, where should you place the pH sensor electrode?

Between the stirring vortex and the side of the glassware

Identify tools that are ideal for cleaning glassware.

Brushes Detergent and water

Review the reversible reactions given, along with the associated equilibrium constant K at room temperature. In each case, determine whether the forward or reverse reaction is favored.

CH3COOH ↔ CH3COO- + H+ Ka=1.8 x 10-5; Reverse A + B ↔ C K=4.9 x 103; Forward Al(OH)3 ↔ Al3+ + 3OH- Ksp=3.7 x 10-15; Reverse AgCl ↔ Ag+ + Cl- Ksp=1.6 x 10-10; Reverse

Aspirin was formed to reduce the irritation of salicylic acid. However, aspirin can still disturb the stomach. Which functional group in aspirin is responsible for stomach irritation?

Carboxylic acid

How should you prepare a buret for titration before loading it with titrant?

Condition the buret with titrant solution.

Match each titration term with its definition.

Solution of an unknown concentration that has another solution slowly added to it; Analyte Process of slowly adding a solution to react with another solution and determine the concentration of one of the solutions based on the reaction between them; Titration Glassware that allows a solution to be precisely and slowly added to another solution; Buret When the required amount of one solution has been added to the second solution to complete the reaction; Endpoint Solution of known concentration that is slowly added to a solution of unknown concentration; Titrant A reagent added to the analyte solution that changes color when the reaction is complete; Indicator

Which species is responsible for the blue color that appears during the iodine clock reaction?

Starch-triiodide complex

Which steps are necessary for cleaning a spill involving broken glass?

Stop the spread of the spill. Soak up any spilled liquid with absorbent material. Pick up large pieces of glass with gloved hands.

How will you detect the endpoint of the titration of the borate ion with HCl?

The bromocresol green indicator will change colors.

Which statement is true about a chemical reaction at equilibrium?

The forward reaction rate is equal to the reverse reaction rate.

Select the term that matches each definition.

The maximum number of moles of a salt that will dissolve in 1 L of solution; Molar solubility The product of the molarities of the dissolved ions, raised to a power equal to the ion's coefficient in the balanced chemical equation; Solubility product constant A decrease in the solubility of an ionic compound as a result of the addition of a common ion; Common ion effect A solution that has dissolved the maximum amount of a compound at a given temperature. Any further addition of salt will remain undissolved; Saturated solution The mass of a salt in grams that will dissolve in 100 mL of water; Solubility

Identify the statements that correctly describe the saturation temperature of a solution.

The temperature at which solid begins to appear from a cooled solution The temperature at which the Ksp value can be calculated

To isolate a single variable when rearranging equations, move all other variables to the ____ of the equation by using ____ on them and remembering to perform that operation ____. Make sure the rearrangement has the target variable ____.

To isolate a single variable when rearranging equations, move all other variables to the other side of the equation by using the opposite function on them and remembering to perform that operation on both sides of the equation. Make sure the rearrangement has the target variable in the numerator, not the denominator.

When an alarm sounds in the laboratory, it is important to respond ____ and remain ____. Listen for any other instructions, turn off any ____ in use, and be prepared to leave immediately.

When an alarm sounds in the laboratory, it is important to respond calmly and remain quiet. Listen for any other instructions, turn off any equipment in use, and be prepared to leave immediately.

To run a spectrophotometry experiment, begin by ____ the spectrophotometer and preparing the samples. Be sure to select the correct ____, then run a measurement on the ____ solution. Follow up by running measurements on ____ solutions. Once data is collected, turn off the instrument, clean the area, and discard the samples.

To run a spectrophotometry experiment, begin by warming up the spectrophotometer and preparing the samples. Be sure to select the correct wavelength, then run a measurement on the blank solution. Follow up by running measurements on sample solutions. Once data is collected, turn off the instrument, clean the area, and discard the samples.

Read each statement regarding food and beverages in the lab and determine if each is true or false.

Tobacco products of all kinds are prohibited in lab; True Chewing gum is okay in the lab as long as you don't blow bubbles; False Food items should not be brought into the lab; True Beverages are allowed in lab as long as they are in containers with lids; False

In lab, you may need to evaluate the odor or smell of a chemical. What is the best way to smell a chemical sample?

Use your hand to gently waft the smell toward you.

Determine where each type of cleaning solution should be discarded after use.

Water used to rinse detergent out of a flask; sink Solvent used to rinse chemicals out of a beaker; waste container Acid solution used to clean a crucible; waste container

Determine the safest option in the lab if you need your vision to be corrected.

Wear corrective glasses or lenses under your safety goggles for the whole experiment, but always check with your TA or Instructor for your school's policy

Match each lab incident to the item of PPE that will protect you from it. Each item of PPE will only be used once.

While picking up a buret, an unknown solution left by a previous solution drips onto your hand; Gloves While checking on a stirring solution, the solution splashes up towards your face; Goggles While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench; Lab coat While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor; Closed-toe shoes

Which is NOT a good source of information about the hazards that affect waste disposal in a chemistry lab?

Your lab partner

Suppose you are studying the kinetics of the reaction between the peroxydisulfate ion and iodide ion. You perform the reaction multiple times with different starting concentrations and measure the initial rate for each, resulting in this table. Experiment 1: [S2O82-](M) 0.27; [I-] (M) 0.38; Initial Rate (M/s) 2.05 Experiment 2: [S2O82-](M) 0.40; [I-] (M) 0.38; Initial Rate (M/s) 3.06 Experiment 3: [S2O82-](M) 0.40; [I-] (M) 0.22; Initial Rate (M/s) 1.76 Based on the data, choose the correct exponents to complete the rate law. rate=k[S2O82-]a[I-]b

a=1; b=1