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Calculate the volume, in mL, of 1.72 M HCl solution that will react with 2.67 mol of CaCO3?
HCI + CaCO3 ---> CaCl2 + H2O + CO2
1. Which of the following defines Hess's Law?
A. Difference of enthalpy changes for the individual steps that make up the overall reaction.
B. Product of enthalpy changes for the individual steps that make up the overall reaction.
C. Sum of enthalpy changes for the individual steps that make up the overall reaction.
D. Sum of standard enthalpy for the individual steps that make up the overall reaction.
2. Flip equations around if necessary to cancel out terms on opposite sides. This is the__step in calculating the enthalpy changes based on the discussion.
A. First
B. Second
C. Third
D. Fourth
3-7. Sequence the given steps in solving for the enthalpy of combustion by writing the number in your notebook. (1-1st step to 5-5th step).
_flip equations around if necessary to cancel out terms on opposite side.
_sum up the individual steps.
_balance the individual equation.
_if necessary, look up standard enthalpies.
_changing the equation around requires a sign change of the H of that individual step.
To analyze the alcohol content of a certain wine, a chemist needs 1.00 L of an aqueous 0.200 M K2Cr2O7 (potassium dichromate) solution. How much a solid K2Cr2O7 must be waited how to make this solution?
Describe also the laboratory procedures that the chemist must employ in preparing K2Cr2O7 solution.
1.) Calculate ΔE if 120kJ of heat energy is absorbed by the system and 40kJ of work
is done on the surroundings.
2.) Find ΔE when a gas absorbs 30kJ of hear and has 15kJ of work done on it.
3.) If the internal energy of a reaction is 480J and the system absorbs 839J of heat
from it’s surrounds,
a. Find the amount of work.
b. Is the work done by the system or work is done on the system? Explain.
Please solve it like this
1. SOLUTION (what formula you use and how you solve it)
2. SOLUTION (what formula you use and how you solve it)
3.A.SOLUTION(what formula you use and how you solve it)
B. EXPLAIN
1. A solution containing 4.50 g of a non electrolyte (i=1) dissolved in 125 g of water
freezes at -0.372ºC. Calculate the molar mass of the solute.
Step 1: First compute the molality of the freezing point equation.
Step 2. Then, from the definition of molality, compute the number of moles
solute, n(solute), in the sample.
Step 3. Solve for the molar mass.
Please solve it like this
STEP1: SOLUTION (what formula you use and how you solve it)
STEP2:; SOLUTION (what formula you use and how you solve it)
STEP3: SOLUTION (what formula you use and how you solve it)
True or False
1. Thermodynamics is the scientific study of the interconversion of heat and other kinds of energy. True or false?
2. A thermodynamic system, which in the case of chemistry is a reaction, with the sorroundings being in a closed system. True or false?
3. The first law of thermodynamics states that energy cannot be created not destroyed, that means that energy is constant. True or false?
4. During a chemical reaction, the energy of the system remains the same as bonds in reactant are broken and the atoms rearrange to form the new bonds of the products. True or false?
5. We can think of the first law of thermodynamics as an energy balance sheet, much like a money balance sheet kept in a bank that does currency exchange. True or false?
To analyze the alcohol content of a wine, a chemist needs 1.00 L of an aqueous 0.200 M K2Cr2O7 (potassium dichromate) solution. How much solid K2Cr2O7 must be weighted out to make this solution?
Describe also the laboratory procedures that the chemist must employ in preparing K2Cr2O7 solution.
9.Given the equation and 𝐻 values(see standard enthalpy of formation f of various 𝑓
∆𝐻°
compounds table given in the discussion ) What is the heat of reaction at 298 K for the reaction:
C(s) + 2 H2(g) CH4(g)
a. -74.8 kJ c. 278 kJ
b. -27.6 kJ d. 296 kJ
10. Knowing the enthalpy of the reaction in number 9, the reaction is:
a. endothermic c. either a or b
b. exothermic d. cannot be determined
8. Given the following equation, CH4(g) + 2O2(g) → CO2(g) + H2O (l)
What is the heat of reaction (kJ) at 298 K for the reaction: (see standard enthalpy of formation
∆𝐻°f of various compounds table given in the discussion )
a. -890. 3 kJ c. 493.3 kJ
b. -393.5 kJ d. 593.2 kJ
5. Zero is the equivalent standard enthalpy formation of;
a. more stable allotropes c. less stable allotropes
b. the reactant of greater concentration d. the reactant of less concentration
6. Which of the following has a standard heat of formation that is NOT equal to zero,
a. Na b. CO2 c. Fe d. Br2
7. Which of the following is NOT TRUE about Hess’s Law?
a. If an equation is reversed the sign of the ∆𝐻 is retained.
b. It is used to find heat changes in either physical or chemical changes
c. It makes possible to measure a heat of reaction without actually doing the experiment
d. It says that if you add two or more thermochemical equations to give a final equation, you
can also add the heats of reaction to give the final heat of reaction.
