chem lab final

Question 1

In the Copper Cycle lab, why did the HCl dissolve the zinc but not the copper?

Answer 1

Zinc is higher in the activity series so its more reactive than hydrogen so it reacts with hydrochloric acid to form soluble zinc chloride and hydrogen. Copper is lower in the activity series so its is less reactive than hydrogen so when copper is added to HCl, the HCl does not react.

Question 2

When a molecule is described as hygroscopic, what does it mean?

Answer 2

if a molecule is hygroscopic it absorbs water molecules from the air

Question 3

what is different between solvent and solute? examples?

Answer 3

solvent is what does the dissolving, solute is what is dissolved. In sugar water, sugar is the solute and water is the solvent.

Question 4

Explain how CTAB (CH3(CH2)15N(CH3)3Br) limited the growth of the CdS particles in the nanoparticle lab.

Answer 4

The CTAB limits the growth of CdS particles because it forms reverse micelles that inhibit the growth of the CdS particles. Reverse micelles have a polar, hydrophilic inside and a hydrophobic outside which is the opposite of soap.

Question 5

Give the name for the compound abbreviated KHP and describe its purpose in the rainwater titration lab.

Answer 5

Potassium Hydrogen Pthalate; used as a primary standard to determine the concentration of the base