288 Answered Questions for the topic Chemistry Lab

10/31/17

Tea contains about 3% caffeine by mass. Assuming each tea bag contained 2.25 g of tea, did you recover the expected amount of caffeine from two tea bags?

So what is the expected amount of caffeine? Is it 0.0675g or is it 0.135g?  In lab, I recovered 0.018g of caffeine

10/28/17

why is it that we can obtain a Raman spectrum

If vibrational transitions correspond to energies in the IR region of the electromagnetic radiation, why is it that we can obtain a Raman spectrum by using a visible wavelength laser as a light... more

10/23/17

Data Table 4: Reaction of Rocks with Hydrochloric Acid

This is from a lab about acid rain

10/22/17

presumptive luminol test

  What role does the hydrogen peroxide play in the reaction? A: Is it the the oxidizing agent and blood in the catalyst?   How would you describe to jury about the scientific basis for this test.

10/20/17

How do I calculate the pressure in a 12.2L vessel that contains 2.34g CO2, 1.73g SO2, and 3.33g Ar at 42 degrees Celsius?

Can you please help me with this problem? Thanks

10/20/17

I am struggling with this AP Chemistry word problem

A 255mL round-bottom flask is weighed and found to have a mass of 114.85g. A few mL of an easily vaporized liquid are added to the flask and the flask is immersed in a boiling water bath. All of... more

10/18/17

Can Flame Test identify any unknown element?

 Explain why or why not

10/17/17

Chemistry Paper Chromatography

A chemist wishes to separate and identify a mixture of substances using paper chromatography. The diagram shows the apparatus used. The solvent is water.The solvent front is allowed to reach the... more

10/16/17

Ion exchange column estimate

The question is: Suppose another student attempts to do an ion exchange on a column that is already nearly saturated with Co2+ and Zn2+. Will his calculated % Co be high or low?

10/15/17

Provide the chemical reaction being demonstrated in the experiment. it should include the starting materials, reagents, and products.

Procedure:1) Accurately weigh approximately 0.40 g of Dimethyl maleate into a 50 mL round bottom flask that possesses a ground glass joint, and record the weight.2) Dissolve the Dimethyl maleate in... more

10/12/17

volume of PCR , is this right?

Reagent stock concentration             Required final concentration                Volume10X Buffer                                                       1X                                       5... more

10/11/17

Compare the reactions of CuCI2 and HCI with AgNO3.

 Compare the reactions of CuCI2 and HCI with AgNO3. Propose a hypothesis to account for the reaction product. Hint: What is the likely chemical formula for the product?

10/11/17

How can this lab illustrate this fact

person is slightly denser than water. Life preservers are made of low density materials.  The average density of a person plus a life preserver is less than density of water- so together they will... more

10/11/17

what process must be performed during clean up; filtration, distillation or chromatography? Why?

What process must be performed during clean up: filtration, distillation or chromatography? Why?

10/05/17

When compound A is partitioned between equal volumes of methylene chloride and water

When compound A is partitioned between equal volumes of methylene chloride and water one finds that the partition coefficient is equal to 1. This means that the compound happens to be equally... more

10/05/17

Percent Composition

Calculate the percent composition of each element, by mass, in Na2CO3*10H2O

10/02/17

where do you think the bacterium that produces HindIII is found?

The optimal working temperature for the restriction endonuclease HindIII is 37°C

09/30/17

Molar abosrptivity

Calculate the molar absorptivity 1. Blue Dye (concentration 40mg/L) (Peak/ λmax is 630) 2.  Red Dye (concentration 60mg/L) (Peak/ λmax is 520) 2. Red Dye (concentration 70mg/L) (Peak/ λmax is... more

09/26/17

Recrystallization problem! ORGANIC CHEMISTRY

200 mg of impure sucrose was weighed out. After recrystallization from water, 225 mg of solid compound was obtained. What happened? How can this be corrected?

09/24/17

toad, has a mass of 13.6 kg. Trevor jumps into a large cylinder containing water. The water level rises 2.50 L. What is the density of the toad?

What is the density of the toad?Express your answer in kg/L.

09/24/17

why the change in the calcium oxalate equilibrium is produced?

We hace experimented with calcium oxalate and i have some observations that could help: First, we made a solution with 5mL of calcium chloride 0,1 M and 5 mL of sodium oxalate 0,1 M. this solution... more

09/17/17

What is the concentration

What is the concentration (in mol L-1) of 12.5 mg of each of disopyramide phosphate and lidocaine hydrochloride dissolved in 250 mL?

09/17/17

Chemistry question

If 20 mg of a drug is dissolved in 250 mL of solvent, how many mg of the drug are present in 5 mL of that solution?
1 2 3 5 7 8 12

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