A) A 50.0-mL volume of 0.15 M HBr is titrated with 0.25 M KOH. Calculate the pH after the addition of 19.0mL of KOH.

Express your answer numerically.

B) A 75.0-mL volume of 0.200 M NH3 (Kb=1.8�10?5) is titrated with 0.500 M HNO3. Calculate the pH after the addition of 13.0mL of HNO3.

C) A 52.0-mL volume of 0.35 M CH3COOH (Ka=1.8�10?5) is titrated with 0.40 M NaOH. Calculate the pH after the addition of 23.0mL of NaOH.

Complete combustion of 2.50g of a hydrocarbon produced 8.14g of CO2 and 2.50g of H2O. What is the empirical formula for the hydrocarbon? Insert subscripts as necessary.

what are the arrhenius definitions for an acid and base? give a chemical equation to demonstrate a strong acid and a weak acid

3. You are hard at work, setting up the apparatus to separate a 40:60 mixture of diethyl ether and toluene by simple distillation. Just as you are getting ready to begin the experiment, your lab partner mistakenly adds a small amount of sodium sulfate into the distillation flask. Would simple distillation still be appropriate or should you switch to fractional distillation? Explain.

Phosphoric acid H3PO4 is manufactured by treating mineral phosphates with concentrated sulfuric acid H2SO4. A typical phosphate mineral, Ca5(PO4)3F, reacts with sulfuric acid as shown by the equation:

Ca5(PO4)3F + 5H2SO4  3H3PO4 + 5CaSO4·2H2O + HF
If 5.00 tons of this mineral is treated with 6.00 tons of sulfuric acid to produce 2.70 tons of

phosphoric acid, what is the percent yield of phosphoric acid?

I am having problems with variables on both sides. I get most of the concepts but I need help with adding fractions into the equations.

Sketch the overlap of orbitals between the HOMO and LUMO that would result in the formation of the preferred product. (anthracene and maleic anhydride diels-alder reaction)

For a parallel reaction A goes to B with rate constant k₁ and A goes to C with rate constant k₂, you determine that the activation energies are 24.6 kJ/mol for k₁ and 116.4 kJ/mol for k₂. If the rate constants are equal at a temperature of 318 K, at what temperature (in K) will k₁/k₂ = 2?

what is the origin of the variety in the properties of polyurethanes

2NO(g) + Br2(g) 2NOBr(g)   A reaction mixture was found to contain 4.70×10-2 moles of NO(g), 4.02×10-2 moles of Br2(g) and 9.28×10-2 moles of NOBr(g), in a 1.00 Liter container. Indicate True (T) or False (F) for each of the following: Indicate True (T) or False (F) for each of the following:

1. In order to reach equilibrium NOBr(g) must be produced.

2. In order to reach equilibrium Kc must decrease.

3. In order to reach equilibrium NO must be produced.

4. Qc is less than Kc.

5. The reaction is at equilibrium. No further reaction will occur.

A mixture of CH4(g) and C2H6(g) has a total pressure of 0.55 atm . Just enough O2(g) is added to the mixture to bring about its complete combustion to CO2(g) and H2O(g). The total pressure of the two product gases is found to be 2.3 atm . Assuming constant volume and temperature, find the mole fraction of CH4 in the mixture. Please type out answer step by step. Thank you!

10. Calculate q, w, ∆U, and ∆H when 50 g of O2(g) is heated at a constant pressure of 1 bar from 50 ºC to 200 ºC. Note: The constant volume heat capacity of O2 is 21.1 J mol-1 K-1.

1. Determine the pH of the buffer solution that is prepared by mixing 867 mL of 0.0403 M HEPES−H (C8H18N2O4S ) to 627 mL of 0.120 M HEPES (C8H17N2O4S− ). Assume the 5% approximation is valid. Report your answer to 2 decimal places.

2. Determine the pH of the HEPES−H/HEPES buffer solution after the addition of 21.2 mL of 2.89 M solution of hydrochloric acid to the existing buffer solution. Assume the 5% approximation is valid.

A pure gold ring and pure silver ring have a total mass of 15.4 g . The two rings are heated to 68.0 ∘C and dropped into a 13.0 mL of water at 21.5 ∘C. When equilibrium is reached, the temperature of the water is 23.7 ∘C.

Part A

What is the mass of gold ring? (Assume a density of 0.998 g/mL for water.)

Express your answer to two significant figures and include the appropriate units.

Part B

What is the mass of silver ring? (Assume a density of 0.998 g/mL for water.)

Express your answer to two significant figures and include the appropriate units.