Chemical Reactions
Predict the product.
Na + O2 -->
Na2O
How many grams of water vapor can be produced from 53.0 g of CH4 assuming an excess of oxygen? The molar mass of CH4 is 16.05 g/mol and the molar mass of water is 18.02 g/mol.
CH4 + 2 O2 --> CO2 + 2 H2O
119 g H2O
Apples turning brown upon cutting is an oxidation-reduction reaction that occurs when oxygen reacts with the surface of the apple. What are two ways to slow down this reaction?
1. Decrease temperature - put in fridge
2. Decrease surface area - don't cut it or not in as many pieces
3. Decrease concentration - place it in an area with less oxygen that can react - like a vacuum sealed bag
What is the pH of an 0.00345 M HCl solution?
2.46
Identify the oxidizing agent in the reaction:
H2 + Br2 --> HBr
Bromine is reduced and is therefore the oxidizing agent
Predict the products: Ag + AlCl3 --> ???
No reaction
If 8 moles of sodium is combined with 5 moles of sulfur, what is the limiting reactant?
2 Na + S --> Na2S
Na - need 10 moles of sodium to react with 5 moles of sulfur.
If the equilibrium constant K = 1.38 and Q for the reaction is 2.00, in which direction is the reaction proceeding?
Left
What is the pOH of a 0.00345 M HCl solution?
11.54
2 Na (s) + Cl2 (g) --> 2 NaCl (s) + 822 kJ
Depends on temperature
Enthalpy is favorable for spontaneous reaction but the entropy is decreasing which is not favorable.
Predict the products: Na + ZnSO4 --> ????
What is the theoretical yield of sodium sulfide if 17.0 g of sodium is combined with 28.0 g of sulfur? The molar mass of Na = 22.99, S = 32.07, Na2S = 78.05 g/mol.
2 Na + S --> Na2S
28.9 g Na2S
The reaction below is first order with respect to A and third order with respect to B. Write the rate law for the reaction.
A + B --> C + D
rate = k[A][B]3
Determine whether the following salt is acidic, basic, or neutral when dissolved in water: Al2(SO4)3
acidic because it comes from H2SO4 (strong acid) and Al(OH)3 (weak base)
What is the enthalpy for the reaction:
NO2 (g) + H2O (g) --> NO (g) + HNO3 (aq)
91.7 kJ/mol
Predict the products: K2S (aq) + MgCl2 (aq) --> ??
MgS (s) + KCl (aq)
What is the concentration of 50.0 mL of an HNO3 solution that is titrated to its equivalence point with 100. mL of 0.0100 M Ca(OH)2?
2 HNO3 + Ca(OH)2 --> Ca(NO3)2 + 2 H2O
0.0400 M HNO3
Write the equilibrium expression (Kc) for the reaction:
CH4 (g) + 2 O2 (g) --> CO2 (g) + 2 H2O (g)
[CO2][H2O]2 / [CH4][O2]2
What is the concentration of an NaOH solution that has a pH of 11.57?
0.003715 M NaOH
In a calorimeter, 10.0 g of urea (N2H4CO) is dissolved in 150.0 mL of water. The temperature changes from 20.4 to 16.7 oC. What is the molar enthalpy of dissolution of urea?
+14.9 kJ/mol
Write the BALANCED chemical equation for the reaction between sodium phosphate and zinc nitrate.
2 Na3PO4 (aq) + 3 Zn(NO3)2 (aq) -->
6 NaNO3 (aq) + Zn3(PO4)2 (s)
When 0.145 g of Al is combined with 25.0 mL of 0.300 M CuCl2, what is the excess reactant and how much of the excess reactant is left over? The molar mass of Al = 26.98, CuCl2 = 134.45, Cu = 63.55, AlCl3 = 133.34.
2 Al + 3 CuCl2 --> 3 Cu + 2 AlCl3
Answer = 0.010 g Al leftover
First find theoretical yield to determine the limiting reactant: 0.512 g from Al or 0.477 g from CuCl2 so CuCl2 is limiting and Al is excess
Then how much Al reacted with CuCl2 - 0.135 g Al reacted.
Leftover = 0.145 - 0.135 = 0.010 g Al
What is the equilibrium constant (Kc) for the reaction below if 1.5 moles of C are placed in a 1.0 L container and reaches an equilibrium where 3.0 moles of B are present.
A2 + B --> 2 C
Kc = 9
HF is a weak acid with a Ka of 3.5 x 10-4. What is the pH of a 0.0500 M solution of HF?
pH = 2.37
Balance the following redox reaction that occurs in acidic conditions:
MnO4- + CH4O --> CH2O2 + Mn2+