Chemistry Answers

the uncertainty associated with a temperature calculated from two readings of a 0^oC and 110^oC thermometer is 1^oC.calculate the percentage uncertainty associated with a temperature difference of 8.0^oC. give your answer to 2 significant figures

In a hittorf experiment ,a student electrolyzed aqueous AgNO3 solution using silver electrodes . The amount of AgNO3 in the anode compartment before electrolysis was 0.228g and the amount after electrolysis was 0.282g. during electrolysis it was found that 0.019g of copper was deposited in the copper colorimeter connected in series with the hittorf cell. Calculate the transport number of Ag+

A solution of AgNO3 containing 12.14g of Ag in 50ml of solution was electrolyzed between pt electrodes . After electrolysis 50ml of the anode solution was found to contain 11.55g of Ag ,while 1.25g of metallic Ag was deposited on the cathode . calculate the transport number of Ag+

In an electrolysis of cuso4 between copper electrodes ,the total mass of copper deposited at the cathode was 0.153g and the mass of copper per unit volume of the anode liquid before and after analysis were 0.79g and 0.91g respectively . Calculate the transport number of cu2+ and so42+

Define half-life. Prove that the half-life of 1st order reaction is independent of the initial concentration of the reactant.

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)