27 Answered Questions for the topic Lab
Finding the Ksp value of Ca(OH)2
A student determined the solubility of Ca(OH)2 in 0.200 M CaCl2 as 0.0026 mol/L. Calculate the Ksp value for Ca(OH)2 using these data. I found this to be =7.03E-8, but it says that I have entered... more
Finding the Average Epsilon and Molarity of Unknown Solution
Stock Solution: 8.8×10-5 MSolution #1: 1.809×10-5 MSolution #2: 1.046×10-5 MYou measure the absorbance of each solution (at λmax = 524 nm) and obtain the following results: ... more
You begin with 1.5000 g of salicylic acid and prepare aspirin according to the outlined procedure in your lab manual. What is your theoretical yield of aspirin?
Hydrogen Emission Spectrum Lab
So I've recently did a hydrogen emission spectrum lab. These were the four wavelengths I got: Red 675 nm Green 570 nm Blue 460 nm Purple 425 nm These are the... more
How to make a buffer?
So I have to make a 0.02 M Sodium Phosphate buffer @ pH of 7, easy enough I use monosodium and disodium phosphate as the acid and base, I used the henderson hasselbach equation. But now I have to... more
What grows on an alkaline peptone broth apart from Vibrio?
I have done an experiment where growth on an alkaline peptone was monitored and then we innoculated a TCBS media, however no growth occured on the TCBS media so i was wondering what else could... more
Williamson Ether Synthesis LAB QUESTION!?
Why use acetonitrile instead of toulene in a Williamson Ether Synthesis? (Phenol, NaH, 1-bromopropane)?Also, why use aqueous Na2CO3 instead of distilled water when extracting?
Empirical formula of the oxide of tin
Hhgghjbb bnbgccccc bbjb. Hbggh bbhfxc ddssyh huh. Hhggcvvbbbbvvvvv b high. Hhgghhbb bhhhhhhb
We can prepare oxygen gas by decomposing hydrogen peroxide. There are many other chemical reactions that generate gases as one of their products.
Lets consider the reaction between zinc metal and hydrochloric acid as such an example. Write a procedure that explains how you would collect the gas produced from this reaction in the laboratory.
The combustion of ethane produces carbon dioxide and water.
The combustion of ethane produces carbon dioxide and water. If 27.6 g C2H6 are burned in the presence of excess ait (O2) and 76.7 g of carbon dioxide are produced, what is the percent yield?
In a lab experiment, 17.5 g of iron II bromide react with 14.2 g of potassium sulfide.
In a lab experiment, 17.5 g of iron II bromide react with 14.2 g of potassium sulfide. Upon completion, 4.3 g of iron II sulfide were obtained. Determine the limiting reactant, theoretical yield... more
Refractive Index - ORGANIC CHEMISTRY LAB
A student attempts to separate a sample of cyclohexane and ethylbenzene by distillation. After the distillation the student obtains an n 20D of 1.4355 for what should be pure cyclohexane with a... more
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
CALCULATING PARTITION COEFFICIENT - Organic Chemistry Lab
1. Calculate the partition coefficient of caffeine in water/methylene chloride from the following data: 10.3 g/100 mL for methylene chloride and 2.04 g/100 mL for water. MY ANSWER: K =... more
Rf values TLC - Organic Chemistry LAB
For my developing solvent, I used 6:4 hexane:ethyl acetate. For my reference spot, I mixed some salicylic acid and ethyl acetate. And for my test spot, I used some impure aspirin and ethyl... more
Calculate the pH of a 0.100 M KCN solution
trying to get concentration
Use the dilution equation to calculate the molar concentration of sodium bsiulfite and potassium iodate after mixing for each th solutions.after mixing hso and after mixing io3
Al+S8 -->Al2S3-How many moles of aluminum are required to produce 56.9 grams of sulfur?-5.0 grams of aluminum sulfide is needed. How many grams of sulfur is required to make it?
CuCO3.Cu(OH)2--> CO2+H2O+2CuO How many grams of Copper II oxide are produced if you start with 1.01 g of Copper II carbonate.
HCl + Na2SO4 → NaCl + H2SO4-If you start with 20.0 grams of hydrochloric acid, how many grams of sulfuric acid will be produced assuming there is 0% error?-How many moles of sulfuric acid should be... more
Mg + NaF → MgF2 + Na-If you start with 5.5 grams of sodium fluoride, how many grams of magnesium fluoride will be produced if there is no error?-Determine how many formula units of sodium fluoride... more
how do you make a 10ml solution with a .40m concentration
I know it has to do with molars and making a solution that we can measure how much light goes through it because we are doing concentration.
Biology Lab - Absorbance vs. Light Intensity
Hello, I recently performed a photosynthesis experiment regarding change in absorbance over time vs. intensity of light. 4 tubes of solutions containing chloroplasts, .1M PO4 buffer, water, and... more
Is citric acid plus baking soda an endothermic reaction?
Please explain if it is endothermic or exothermic?