1. Calculate the pH and the concentrations of all species present in a .0230 M HPO4- (Ka = 4.90 x 10-10)
2. Calculate the pH and the concentrations of all species present in a 3.20 x 10-5 M CH3CO2H (Ka = 1.70 x 10-5)
In: Chemistry
In 1783, Jacques Charles launched his first balloon filled with hydrogen gas, which he chose because it was lighter than air. This balloon, which had a volume of 31 000L at STP, reached an altitude of 1000m, where the pressure was 651 mmHg and the temperature was -9 degrees C. What was the volume, in liters, of the balloon at these conditions?
In: Chemistry
An aqueous solution containing 34.2g of an unknown molecular (nonelectrolyte) compound in 143.1g of water was found to have a freezing point of -1.5?C. Calculate the molar mass of the unknown compound.
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What is the structural and functional difference between polysaccharides and glycosaminoglycans
In: Chemistry
The incredible length of biological polymers (sometimes tens of thousands of monomers) often results in the formation of a tertiary, 3-D structure. An example of this is in globular proteins. Which of these is NOT a force of attraction which usually acts between the different sections of the polypeptide chain of a globular protein?
| 1. |
Van der Waals' forces |
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| 2. |
Hydrogen bonds |
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| 3. |
ionic bonds |
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| 4. |
Metallic bonds |
In: Chemistry
354 mL of 0.21 M formic acid HCOOH was mixed with 126 mL of 0.9 M NaOH. What will be the final pH?
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0.10 g of Fe3O4 reacts with excess O2 to give Fe2O3 in 20.36% yield according to the following balanced equation. Calculate the theoretical yield and the actual yield of Fe2O3(s).
4Fe3O4(s) + O2(g) --> 6Fe2O3(s)
In: Chemistry
Suppose you have the following reaction at equilibrium:
C(s) + 2H2(g) = CH4(g), ΔH = −74.8 kJ
What changes are expected to occur if the pressure of the system was increased? You may select multiple answers.
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The temperature would increase above the expected temperature increase resulting from the increased pressure. |
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The concentration of H2(g) would decrease |
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The amount of C(s) present would decrease |
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The concentration of CH4(g) would increase |
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No change in the equilibrium would occur. |
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The concentration of CH4(g) would decrease |
In: Chemistry
A solution was prepared by dissolving 0.0258 mol disodium phosphate in 500.0mL of deionized water. Phosphoric acid has the following pKa values: pKa1 = 2.148 , pKa2 = 7.198 , pKa3 = 12.375.
a) What was the pH of the resulting solution?
b) What was the concentration of H2PO4- in the solution?
In: Chemistry
a) Of the chemical bonding types often found in minerals, which is the strongest and which is the weakest? Why?
b) Water molecules in ice are an example of what type of bond? Explain.
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Suppose that 25.14 g of ice at -8.7°C is placed in 69.18 g of water at 98.1°C in a perfectly insulated vessel. Calculate the final temperature. (The molar heat capacity for ice is 37.5 J K-1 mol-1 and that for liquid water is 75.3 J K-1 mol-1. The molar enthalpy of fusion for ice is 6.01 kJ/mol. You must answer in Kelvin, not °C.)
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Potassium oxalate is a monohydrate salt that forms colorless, odorless crystals. Oxalic acid is a diprotic acid with Ka1 = 5.4 x 10-2 and Ka2 = 5.3 x 10-5 . (a) If 1.842 g potassium oxalate monohydrate is dissolved in enough water to make 100.0 mL of solution, what will be the pH of the solution? (b) What will be the equilibrium concentration of the fully protonated oxalic acid?
In: Chemistry
Calculate ΔS if 2.10 mol of liquid water is heated from 0.00 ∘C to 13.5 ∘C under constant pressure if CP,m=75.3J⋅K−1⋅mol−1.
The answer the the problem above is 7.62 J/K
The melting point of water at the pressure of interest is 0.00 ∘C, and the enthalpy of fusion is 6.010 kJ⋅mol−1. The boiling point is 100. ∘C, and the enthalpy of vaporization is 40.65 kJ⋅mol−1. Calculate ΔS for the transformation of the same amount of water
H2O(s,0.00∘C) →H2O(g,100.∘C)
Can you help me solve the second question?
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A reaction of 59.5 g of Na and 48.7 g of Br2 yields 57.1 g of NaBr. What is the percent yield?
In: Chemistry
Trichloroethylene, a widely used degreasing solvent for machine parts is produced in a two-step reaction sequence. Ethylene is first chlorinated to yield tetrachloroethane, which is dehydrochlorinated to form trichloroethylene.
C2H4 (g) + Cl2 (g) ? C2H2C14 (1) + H2 (g): ?H?? = �385.76 kJ/mol
C2H2C14 (l) ? C2HCl3 (l) + HC1 (g)
The standard heat of formation of liquid trichloroethylene is
�276.2 kJ/mol
(a) Use the given data and tabulated standard heats of formation of
ethylene and hydrogen chloride to calculate the standard heat of
formation of tetrachloroethane and the standard heat of the second
reaction.
(b) Use Hess�s law to calculate the standard heat of the reaction
C2H4 (g) + 2 C12 (g) � C2HCI3 (l) + H2 (g) + HCI (g)
(c) If 300 mol/h of C2HCl3 (l) is produced in the reaction of part
(b) and the reactants and products are all at 25�C and I atm, how
much heat is evolved or absorbed in the process? (Assume Q =
?H)
In: Chemistry