Pre-lab questions for a Saponification lab:

A student assembled the reflex apparatus. Later the joint was seized and the RBF had to be broken to disassemble the apparatus. What was the cause of this? How could it have been prevented?

Filtering the soap using a washcloth exposes your hands to a very basc solution. What should you be doing to protect your hands from basic hydrolysis?

Thank you!

Your lab is supplied with 1.500 F solutions of HCL, NaOH, acetic acid, (Ka = 1.75x10^-5) sodium acetate. Prepare a 400.0mL o a 0.1000M acetate buffer: pH 4.622 using specified reagents

a) 1.000 F acetic acid and 1.000 F sodium acetate

b) 1.000 F sodium hydroxide

c) 1.000 F sodium acetate and 1.000F HCl

Please show all work!

11.

A 150.0 mL solution of 2.713 M strontium nitrate is mixed with 220.0 mL of a 2.401 M sodium fluoride solution. Calculate the mass of the resulting strontium fluoride precipitate.

mass: g

Assuming complete precipitation, calculate the final concentration of each ion. If the ion is no longer in solution, enter a 0 for the concentration.

[Na+] M

[NO−3] M

[Sr2+] M

[F−] M

Complete the stoichiometry of each reaction, making sure both stoichiometry and charge balance are correct. That is, find the values of the coefficients A, B, C, etc., for each reaction. Show your work and explain your reasoning. [2 Points each]

(a) Oxidation of nitrite to nitrate (a chemoautotrophic process): A·O2 + B·NO2- = C·NO3-

(b) Oxidation of organic matter using nitrite (a step of denitrification, a heterotrophic reaction):

A·CH2O + B·NO2- + C·H+ = D·CO2 + E·N2 + F·H2O
(c) Oxidation of ammonium with nitrite (anammox, a chemoautotrophic process):

A· NH4+ + B·NO2- = C·N2 + D·H2O

[Hint: start by writing the 2 half-reactions for each full reaction, including the number of electrons produced by the oxidation half-reaction, and the numbers of electrons required for the reduction half-reaction. Then balance H+ and H2O if required by stoichiometry, and sum the half reactions, each multiplied by the factor required to have the same number of electrons produced and consumed. End by simplifying terms present in both sides.]

A sample of concrete with a density of 2.35 g/cm³ has a hydrogen content of 0.0085 weight fraction. a) what is the atom density of hydrogen in the concrete? b) what is the atom density of hydrogen in water at room temperature? c) how do these numbers compare (comment)?

Silicon dioxide and solid carbon react to form solid silicon and carbon monoxide.What is oxidized?

2. How would Evelyn Effec affect the products formed from the dehydration of 2-methylhexanol (My product is 1-methylcyclohexene)? How could you modify the experiment to check for the Evelyn Effect?

Natural gas is primarily methane, CH4, and is used to heat homes. A typical home is approximately 2000 ft2 and the ceilings are 8 ft high. The following data may be helpful: The heat capacity of air is 1.01 J/g·K and the and the enthalpy of combustion of methane is -890.8 kJ/mol. Assume that the molecular weight of air is the same as nitrogen, its major component. How many grams of methane are required to raise the temperature in the home from 35°F to 66°F? How many grams of CO2 does this reaction produce?

Two 20.0 g ice cubes at −11.0 ∘C are placed into 225 g of water at 25.0 ∘C. Assuming no energy is transferred to or from the surroundings, calculate the final temperature, Tf, of the water after all the ice melts.

Tf= ∘C

Which of the following would be expected to lower the Tm for a phospholipid bilayer?

replacing a lipid containing unsaturated fatty acids with one containing saturated fatty acids.

replacing a lipid containing 18-C fatty acids with one containing 16-C fatty acids.

adding ions to bind to charged groups in the polar head groups.

decreasing the concentration of phospholipids.

Show all work for life saving rating *****

Make separate (50ml) of .05M chromium (III) nitrate and a 0.20M Cobalt (II) nitrate in distilled water.

After making the stock solution make five standards in which the absorbance falls from 0.1 A.U to 1AU

Calculate the volume of nitrogen dioxide produced at 712.5 torr and 23.3°C by the reaction of 7.85 cm3 copper (density = 8.95 g/cm3) with 207.3 mL of concentrated nitric acid if the acid has a density of 1.42 g/cm3 and contains 68.0% HNO3 by mass). Cu(s) + 4HNO3(aq) → Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l)

why do atoms aproach each other?

Why is copper sulfate (CuSO4 ) not commonly found as a naturally-occurring copper ore mineral, even though it is easily made during leaching of other copper minerals?

4.60 mol of solid A was placed in a sealed 1.00-L container and allowed to decompose into gaseous B and C. The concentration of B steadily increased until it reached 1.10 M, where it remained constant.

A(s) <===> B(g) + C(g)

Then, the container volume was doubled and equilibrium was re-established. How many moles of A remain?