1. Farmers who raise cotton onve used arsenic acid, H3AsO4, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K1 = 2.5 * 10-14, K2 = 5.6 * 10 -8 , and K3 = 3 * 10 -13 .
What is the pH of a 0.500 M sol'n of arsenic acid?
answer ) 1.96
3. A solution is prepared by adding 0.10 mol of KCH3COO, to 1.00 L of water.
Which statement about the sol'n is correct?
a) the sol'n is basic.
b)the sol'n is neutral
c) the sol'n is acidic
d) the concentrations of K+ ions and CH3COO- ions will be identical
e) the concetnration of CH3COO- ions will be greater than the concetnraion of K+ ions.
4. A sol'n is prepared by adding 0.10 mol of KCL, to 1.00 L of water. Which statement about the sol'n is correct?
a) the sol'n is basic
b) the sol'n is neutral
c) the sol'n is acidic
d)one need to know the temperature before any of the above predictions can be made.
e) the values for Ka and Kb for the species in sol'n must be known before a prediction can be made.
I already knew the answers except #2, but I don't know the reason why.
Please explain the questions to me. Thanks!
In: Chemistry
Consider the hypothetical heteronuclear diatomic molecule XY where Y is more electronegative than X. Using only the p orbitals from each atom, construct a molecular orbital diagram. For each unique type of bond and anti-bond, sketch a picture of the molecular orbital resulting from the mixing of the atomic orbitals. Redundant molecular orbitals (i.e. those that only differ in orientation) need not be drawn. What is the bond order when there are 6 total electrons (X+Y p electrons)? Is that molecule paramagnetic or diamagnetic? What happens to the bond order if you add 1 more electron (7 total electrons)? Is that molecule paramagnetic or diamagnetic?
In: Chemistry
Aspirin can be prepared from salicylic acid ( C 7 H 6 O 3 ), which has a molar mass of 138.12 g/mol, and acetic anhydride ( C 4 H 6 O 3 C 4 H 6 O 3 ), which has a molar mass of 102.04 g/mol. The density of acetic anhydride is 1.082 g/mL.
C 7 H 6 O 3 + C 4 H 6 O 3 ⟶ C 9 H 8 O 4 + C 2 H 3 O 2
What is the theoretical yield of aspirin ( C 9 H 8 O 4 ), which has a molar mass of 180.15 g/mol, possible when reacting 3.19 g of salicylic acid with 3.75 mL of acetic anhydride?
In: Chemistry
The activation energy of an uncatalyzed reaction is 70.0 kJ/mol. When a catalyst is added, the activation energy (at 20.0 C) is 42.0 kJ/mol. Theoretically, to what temperature (C) would one have to heat the solution so that the rate of the uncatalyzed reaction is equal to the rate of the catalyzed reaction at 20. 0 C? Assume the frequency factor A is constant, and assume the initial concetrations are the same.
In: Chemistry
a. Give one safety hazard when using the Bunsen burner
and one precautionary to avoid this hazard.
b. What safety measures do you need to practice when using the oven
to dry the solid product?
In: Chemistry
To prevent brain damage, a standard procedure is to lower the body temperature of someone who has been resuscitated after suffering cardiac arrest. What is the physiochemical basis for this procedure?
In: Chemistry
The pH of an aqueous solution of 0.572 M caffeine (a weak base with the formula C8H10N4O2) is:
In: Chemistry
Two thousand (2,000) pigs in the growing-finishing stage (60 kg) are housed at a temperature (Ti) of 15 C. The indoor relative humidity (RHi) should not exceed 70%. The outdoor air conditions are To = -10 C and RHo = 50%. The UA value for the structure is 10,050 J/s.C. Will supplemental heat (Qsupp) be required for this structure, if so how much (J/s)?
In: Chemistry
At what point(s) during the oscillation of a spring that obey's Hooke's law is the force on the mass the greatest?
In: Chemistry
What is the difference between a reversible and irreversible process in chemistry?
In: Chemistry
Given these reactions,
X(s) + 1/2 O2(g) -----> XO(s) Delta H = -699.3 kJ/mol
XCO3(s) -------> XO(s) + CO2(g) Delta H = +328.3 kJ/mol
what is Delta Hrxn for this reaction?
X(s) + 1/2 O2(g) + CO2(g) -------> XCO3(s) Delta H = kJ/mol
In: Chemistry
Calculate the equilibrium constant for the reaction between Ni2+(aq) and Zn(s) under standard conditions at 25∘C.
In: Chemistry
4.
Which reactions are redox reactions?
Choose at least one answer.
| A. hydrochloric acid reacting with nickel metal to form hydrogen gas and aqueous nickel(II) chloride | ||
| B. sodium bromide reacting with chlorine to form sodium chloride and bromine | ||
| C. sodium hydroxide reacting with aluminum chloride to form solid aluminum hydroxide and sodium chloride | ||
| D. sodium hydroxide reacting with hydrochloric acid to form water and sodium chloride | ||
| E. sodium hydroxide reacting with potassium to form potassium hydroxide and sodium | ||
| F. acetic acid reacting with sodium bicarbonate to form carbon dioxide, water and sodium acetate |
In: Chemistry
When tert-butanol is placed in the presence of excess equimolar amounts of chloride and bromide ions in aqueous acid experimental data indicates 45% tert-butyl chloride and 55% tert-butyl bromide is obtained. On the other hand, when n-butanol is placed in the presence of excess equimolar amounts of chloride and bromide ions in aqueous acid experimental data indicates 16% of n-butyl chloride and 84% n-butyl bromide is obtained. Now when n-butanol is placed in the presence of excess equimolar amounts of chloride ions and bromide ions in acid dimethyl sulfoxide the experimental data provides an 84% n-butyl chloride and 16% n-butyl bromide as the outcome.
1.) write balanced chemical equations for all three reactions (hint: account for mole ratios!).
2.) draw complete mechanisms for all three reactions.
3.) calculate the theoretical yield for the chlorides and bromides if each reaction was started with 5.55ml of the corresponding alcohol, using an aqueous acid media.
Sample: tert
Theoretical g of chloride
Theoretical g of bromide
Sample: n-
Theoretical g of chloride
Theoretical g of bromide
In: Chemistry
Carbonic acid, H2CO3, is a weak diprotic acid. In a 0.1 M solution of the acid, which of the following species is present in the largest amount?
|
H2CO3. |
||
|
H3O+ |
||
|
HCO3 |
In: Chemistry