calculate the concentrations of H+, HCO- and CO3^2- in a 0.025 M H2CO3 solution

5.         From the information below, determine the mass of substance C that is formed if 45.0 g of substance A reacts with 23.0 g of substance B, assuming that the reaction between A and B goes to completion.

A. Substance A is a solid that consists of a Group 13 (3A) metal (boron is not a metal!) and carbon; the m% C in substance A is 57.2%. It reacts with substance B to form substances C and D. 4.0 x 10¹⁶ formula units of substance A weighs 8.371 micrograms.

B. 47.9 g of substance B contains 5.36 g H and 42.5 g O.

C.   When 10.0 g of substance C is burned in excess oxygen, 33.8 g of CO₂and 6.92 g of H₂O are produced. The molar mass of substance C is M_C = ~26 g/mol.

D. Substance D is the hydroxide of the metal in substance A.

Discuss how a distillation works; also include the difference between a simple and a fractional distillation. Why is fractional distillation used in preparation of cyclohexene?

Consider the titration of 25.0 mL of 0.0200 M MnSO4 with 0.0100 M EDTA in a solution buffered to pH=6.00. Calculate pMn2+ at the following volumes added EDTA, and use your data to sketch a titration curve for they hypothetical sample: 0, 20.0, 40.0, 49.0, 49.9, 50.0, 50.1, 55.0, and 66.0 mL.

Find information on:

1. epinephrine

2. cholic acid

3. ibuprofen (both enantiomers)

4. naproxen

To get full credit (4 pts) you must: 1. Give molecular formula and structure

2. Identify each carbon’s hybridization

3. Identify one stereocenter and it’s configuration

4. Identify the molecule’s importance and/or application

A 6.79-L cylinder contains 2.00 mol of gas A and 3.96 mol of gas B, at a temperature of 31.5 °C. Calculate the partial pressure of each gas in the cylinder. Assume ideal gas behavior.

A solution of .05 M glutamic acid is at its isoelectric pH. Calculate:
i) the approximate concentration of its major isoelectric form
ii) the approximate concentration of the completely protonated form
iii) How may forms are present in solution at even miniscule concentrations?

What methods and calculations are used in order to obtain the pH of a system with changing dynamics? Please include a mathematical example to accompany each case and solve at pH 3, 7 and 10.

a) Addition of weak base to weak acid

b) Addition of strong base to weak acid

c) Addition of weak base to strong acid

d) Addition of strong base to strong acid

Which of the following samples contains the largest total number of atoms? Please show work

a) 0.10 moles of P4O10

b) 0.20 moles of P4O6

c) 0.30 moles of N2O5

d) 0.40 moles of N2O4

e) 0.50 moles of BiF3

After running a base catalyzed hydrolysis of nicotinitrile with anion-exchange resins, how can I determine if I ended up with niacin or nicotinamide, without melting point ranges, or NMR?

6. In Experiment 13, the class studied the aquation of [Co(NH3)5Cl]2+. Below are sets of absorbance data taken during this study using 1.2 x 10-2 M [Co(NH3)5Cl]2+ in 0.1 and 0.3 M HNO3.

0.1 M HNO3

t (min) A @ 550 nm

15 0.346

30 0.314

40 0.300

60 0.280

75 0.264

0.3 M HNO3

t (min) A @ 550 nm

15 0.492

30 0.446

40 0.420

60 0.393

75 0.372

The first-order rate constants can be determined using the following equation ln(A-A) = -kt + ln(A0-A) where A0 is the initial absorbance at 550 nm before aquation began to occur.

A. (10 POINTS) What is the value of A? (show work)

B. (20 POINTS) Plot ln(A-A) vs. t and give the values of k and A0 for both sets of data above (attach both plots and show all work).

C. (5 POINTS) Based upon the above rate constants, by which mechanism to you believe that the aquation is occurring? Explain.

A sample has a Subscript 6 Superscript 14 Baseline Upper C activity of 0.0020 Bq per gram of carbon. (a) Find the age of the sample, assuming that the activity per gram of carbon in a living organism has been constant at a value of 0.23 Bq. (b) Evidence suggests that the value of 0.23 Bq might have been as much as 37% larger. Repeat part (a), taking into account this 37% increase.

13# A 29.3 g of a new element was isolated from 660 kg of the ore molybdenite. The percent by mass of this element in the ore molybdenite was:

A) 44%

B)6.6%

C)29.3%

D) 0.0044%

E)19.3%

14# SO2 reacts with H2S as follows:

2H2S + SO2----3S + 2H2O

When 7.50g of H2S reacts with 12.75 g of SO2, which statement applies?

A) 6.38g of sulfur are formed

B) 10.6g of sulfur are formed

C)0.0216 moles of H2S remain

D) 1.13g of H2S remain

E) SO2 is the limiting reagent

15# Roundup,an herbicide manufactured by Monsanto, has the formula C3H8NO5P. How many moles are there in a 295.1-g sample of roundup?

18# You mix 55ml of 1.00 M silver nitrate with 25Ml of 0.84M sodium choride. What mass of silver choride should you form ?

Both starch and cellulose are polymers of glucose. Why is one, starch, readily digestible by a variety of organisms, including humans and the other digestible by a limited number of organisms? What prevents cellulose from being digested by most organisms? Locate another polymer that exhibits similar properties, and describe it here.

A red blood cell is placed into each of the following solutions. Indicate whether crenation, hemolysis, or neither will occur.

Solution A: 3.61{\rm \\%} (m/v) NaCl

Solution B: 4.16{\rm \\%} (m/v) glucose

Solution C: distilled H2O

Solution D: 7.79{\rm \\%} (m/v) glucose

Solution E: 5.0% (m/v) glucose and 0.9% (m/v) NaCl

Drag each solution to the appropriate bin.