CHE 111

Which of the following would be the best choice for neutralizing spilled acid?

Add sodium bicarbonate to the spill.

Filter paper is most often used in the laboratory to separate

solids from liquids.

What are two uses of a vacuum filtration setup? Select all that apply

separation of a solution and a precipitate
drying a filtered solid

Gravimetric Analysis uses what property to quantitatively determine the how much of one or more constituents is present?

Mass

Which of the following statements are true about the conditions for a successful recrystallization?

The desired compound has low solubility in room temperature solvent.

Rank the procedure for simple recrystallization (for purification).

Start
1.dissolve in a minimum amount of hot solvent
2. filter out solid impurities
3. allow to cool until crystals form
4. filter and wash the crystals
end

An aspirin sample is synthesized from salicylic acid and acetic anhydride, and then tested for purity using an iron(III) chloride solution. The resulting solution is a deep purple color. What caused the purple color?

The iron(III) chloride solution reacted with unreacted salicylic acid, forming the purple iron(III) salicylate complex.

What does the deep purple colored iron(III) chloride solution indicate about the reaction mixture?

The aspirin sample is contaminated with salicylic acid.

Suppose a student conducted the synthesis of salicylic acid and obtained 245 mg of the crude product. The student then used water to recrystallize the product. After recrystallization, the mass of the salicylic acid was 255 mg. What would be a possible ex

The salicylic acid was not completely dried after the recrystallization. Dry it and reweigh.

The salicylic acid was not completely dried after the recrystallization. Dry it and reweigh.

dilute acetic acid solution

Which of the following are characteristics of a primary standard?

high purity
high molar mass
low cost
stability in the atmosphere

You need to standardize a base solution by titration with an acid solution of known concentration. You find the volume of the acid solution needed to reach the endpoint for a sample of the base solution. Arrange the steps below in the order that will allo

first
1.write a balanced equation for the reaction between the analyze and the titration
2.calculate the number of moles of titrant using the volume of titrant required and the concentration of titrant
3. Calculate the number of moles of analyte using the

Why is a plastic bottle generally preferred to a glass bottle to store NaOH?

Sodium hydroxide reacts slowly with glass, forming sodium silicate.

Why is potassium acid phthalate (KHP) (KHC8H4O4, MM = 204.227 g/mol) so widely used as a primary standard in acid-base titrations? Select all that apply.

It is available in high purity.
It is stable to air.
It has a relatively high molar mass.

he student weighs 0.9599 g of potassium acid phthalate (KHP) into a flask and adds water from a graduated cylinder to dissolve it. Why doesn\'t she measure the volume of water with a more accurate device?

The volume of water added is not important because the titration equivalence point depends only on the number of millimoles of potassium acid phthalate and not its concentration.

Why is freshly distilled or deionized water used in this standardization?

There is little CO2 in freshly deionized or distilled water.

What is the purpose of the coffee cup in a coffee cup calorimetry experiment?

The coffee cup insulates the experiment, minimizing heat loss to the environment.

In a calorimetry experiment the calorimeter heat capacity, or calorimeter constant Ccal, must be determined before finding heats of neutralization or formation. Sort the steps listed below into the correct order for calculating the heat capacity of a calo

1. record the initial temp of warm and cold water
2. add warm water to cool water and record final temp
3. calculate the change in temp of cool and warm water
4. find cool and warm using q=mcT
5. use qsurr=-qsys to find qcal
6. find Ccal using cal and del

A spectrophotometer measures the transmittance or the absorbance, or both, of a particular wavelength of light after it has passed through a liquid sample. The liquid sample holder is commonly known as a cuvette. Select the statement from the following th

A cuvette has entirely clear walls so light can pass easily through it.

SDS stands for

safety data sheet

SDS are available for

all chemicals produced

What is the primary function of forceps in the chemistry lab?

grasping small objects