Homework answers / question archive / 1) Explain why three carbons could not have two triple bonds between them

1) Explain why three carbons could not have two triple bonds between them

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1) Explain why three carbons could not have two triple bonds between them. 

2) Rank the compounds NH3, CH4, and PH3 in order of increasing boiling point.Choices:A) NH3 < CH4 < PH3

B) CH4 < NH3 < PH3

C) NH3 < PH3 < CH4

D) CH4 < PH3 < NH3

E) PH3 < NH3 < CH4

3) I'm working on this:Calculate the solubility of Pb(CN)44-51Pb(CN)4+4-Ksp = [X]144.8 X 10-512

in water. Ksp for Pb(CN) = 4.8 X 10

-----> Pb + 4CN

[4X]

= 16x

Do I have this right so far?

4) What is the pH of a solution that has an initial HA concentration of 0.62 M, with a Ka-7HA (aq) + H23+-

 = 1.4 x 10? Answer to two decimal places.

O (l) ? HO (aq) + A (aq)

5) Which substance would be expected to have the lowest boiling point?Choices:A) PH3 B) H2SC) H2O  D) CH4

5) What is the theoretical mass of xenon tetrafluoride that should form

when 67.1 grams of xenon is reacted with 67.1 grams of F2?
Xe (g) + 2 F2 (g) → XeF4 (g)

6) What is the theoretical mass of xenon tetrafluoride that should form

when 67.1 grams of xenon is reacted with 67.1 grams of F2?
Xe (g) + 2 F2 (g) → XeF4 (g)

7) Zinc metal, Zn, reacts vigorously with hydrochloric acid, HCl, to

produce zinc chloride, ZnCl2, and hydrogen gas, H2. If 10.31 moles of hydrogen gas is produced, how many moles of HCl reacted?
Zn (s) + HCl (aq)  → ZnCl2 (aq) + H2 (g)  (unbalanced)

8) Barium carbonate (BaCO3) is used in rat poison, bricks, ceramic glazes,

and cement. The Ksp of BaCO3 is 2.58 x 10-9.
a) Is BaCO3 acidic, basic, or neutral? How can you tell?
b) What is the molar solubility of BaCO3 in pure water?
c) What is the pH of a saturated BaCO3 solution? The Ka of the bicarbonate ion (HCO3-) is 5.6 x 10-9)d) If you were to titrate a saturated solution of BaCO3, what would you use as the titrant? Qualitatively sketch the titration curve. Clearly label your axes, the buffer region, and indicate whether the equivalence point is acidic, basic, or neutral.

10) Given that the stepwise dissociation constants for phosphoric acid are:Ka1-3a2-8a3-13

 = 7.5×10; K = 6.2×10; K = 4.8×10

To prepare 1.20 L of a buffer solution having an ionic strength of 0.150 and a pH of 7.50 would require:

Answer to 3 sig figs. 

a) (mass) of Na₂HPO₄(anhydrous) and 

b) (mass) of NaH₂PO₄(anhydrous).

11) please help with the question below

the enthalpy of reaction under std. state conditions at 25oC for the combustion of CO,

                        CO(g)    +      ½ O2(g)  —>  CO2(g)            

is -282.984 kJ/mol and the Gibb's free energy at the same temperature is -257.191 kJ/mol.  At what temperature will this reaction no longer be spontaneous?

12) Why would it be important that scientist world-wide accept and use

the SI system for making and reporting measurements?

13) Do you think that the seed banks and other facilities for collecting genetically diverse organisms are important? Why or why not?

14) At a certain T, the solubility of AI(OH)34-3Calculate Ksp of AI(OH)3

in 0.40M AIPO solution is given as 4.63x10M.

at this temperature.

15) Selenium-75, a β emitter with a half-life of 120 days, is used medically for pancreas scansPart A 

Approximately how long would it take for a 0.050 g

 sample of selenium-75 to decrease to 0.010 g

Express your answer using two significant figures.

Part B 

Approximately how much selenium-75 would remain from a 0.050 g

 sample that has been stored for one year? (Hint: How many half-lives are in one year?) 

Express your answer using two significant figures

16) Construct a simple flowchart summarizing the separation and analysis of Group II cations (Sn+2+2+3+2

, Cd, Bi, Cu) from the unknown solution.

17) In acid solution, potassium permanganate reacts with H2O2 to form Mn2 +:

5H2O2 + 2MnO4- + 6H + -------> 5 O2 + 2Mn2 + + 8H2O

In neutral solution they react with MnSO4 forming MnO2:

3Mn2 + + 2MnO4- + 4OH- -------> 5MnO2 + 2H2O

Calculate the milliliters of 0.1 M KMnO4 that will react with 50 ml of 0.2 M H2O2 and with 50 ml of 0.2 M MnSO4.

18) C14 H22 O2(aq) + H2O2(aq) → C14 H20 O2(aq) + 2H2O(l)

Determine the value of ?Hrxn for the above reaction between C14 H22 O2(aq) and H2O2(aq) using Hess's Law and the following two thermochemical equations. Show your work.

2C14 H22 O2(aq) + O2(g) → 2C14 H20 O2(aq) + 2H2O(l), ?Hrxn = -202 kJ/mol

2H2O2(aq) → O2(g) + 2H2O(l), ?Hrxn = -196 kJ/mol