The half life of ¹⁴C is 5730 years. What fraction of the ¹⁴C nuclei in a sample are left after 8140 years?

You are studying the reaction of iodine with a ketone to produce iodoketone with the following equation:

            I₂ + ketone → iodoketone + H⁺ + I^-

Data for initial rates and concentrations are given in the table below:

-d[I₂]/dt                        [I₂]                   [ketone]                        [H⁺]

mol^-1 L s^-1                     M                     M                                 M

7 x 10^-5                         5 x 10^-4             0.2                               1.0 x 10^-2

7 x 10^-5                         3 x 10^-4             0.2                               1.0 x 10^-2

1.7 x 10^-5                      5 x 10^-4             0.5                               1.0 x 10^-2

5.4 x 10^-5                      5 x 10^-4             0.5                               3.2 x 10^-2

Calculate the average rate coefficient in te above question.

A hot lump of 43.0 g of iron at an initial temperature of 62.6 °C is placed in 50.0 mL of H2O initially at 25.0 °C and allowed to reach thermal equilibrium. What is the final temperature of the iron and water given that the specific heat of iron is 0.449 J/(g·°C)? Assume no heat is lost to surroundings.

Urea (CH4N2O) is a common fertilizer that can be synthesized by the reaction of ammonia (NH3) with carbon dioxide as follows: 2NH3(aq)+CO2(aq)→CH4N2O(aq)+H2O(l) In an industrial synthesis of urea, a chemist combines 120.6 kg of ammonia with 211.4 kg of carbon dioxide and obtains 181.4 kg of urea.

Part A) Determine the limiting reactant.

Part B)Determine the theoretical yield of urea.

Part C) Determine the percent yield for the reaction.

A silver block, initially at 55.4 ∘C, is submerged into 100.0 g of water at 24.0 ∘C, in an insulated container. The final temperature of the mixture upon reaching thermal equilibrium is 27.8 ∘C. What is the mass of the silver block? Express your answer to two significant figures and include the appropriate units.

1.a) If ΔE > 0 then energy is being absorbed by the system.

True

False

1.b) If ΔE_system is positive then ΔE_surrounding must be:

Iron(III) oxide reacts with carbon monoxide according to the equation:
Fe2O3(s)+3CO(g)→2Fe(s)+3CO2(g)
A reaction mixture initially contains 22.90 g Fe2O3 and 15.78 g CO.

Once the reaction has occurred as completely as possible, what mass (in g) of the excess reactant is left?

The steroid hormone estriol contains only C, H, and O; combustion analysis of a 3.47 mg sample yields 9.53 mgCO2 and 2.60 mgH2O. On dissolving 7.55 mg of estriol in 0.500 g of camphor, the melting point of camphor is depressed by 1.97 ∘C. [For camphor, Kf = 37.7 (∘C⋅kg)/mol.]

i. What is the molecular weight of estriol?

ii. what is the probable formula?

2) The number of moles of ions in 30.0 mL of 3.00 M Na2SO4 is ________ moles.

The question I have is what are the balanced equations and net ionic equations for the four following scenarios.

1. Dissolving solid NaOH in water

2. Neutralization reaction of NaOH (aq) with 1.00 M HCl mass of cup and NaOH soultion

3. Neutrlization reaction of solid NaOH with 1.00 HCl

4. Neutralization reaction of NaOH (aq) with 1.00 M acetic acid

briefly explain on a fundamental chemical basis what effect adding charges has on the polymer chain and how this relates to polarons and charge transport within the organic material. Then describe three different methods or devices through which charge carriers are added to an OSC, the main purpose or function of each

Discuss how well VSEPR predicts shape, how shape contributes to chemical reactivity, and how computer modeling can help support your predictions.

It takes 25 ml of 0.40 M nitric acid solution to completely neutralize 50.0 ml of 0.20 M NH3 solution (i.e. to reach the equivalence point). What is the pH of the equivalence point?(Kb NH3 = 1.8x10^-5)

If you were to leave calcium metal in contact with oxygen at a partial pressure of 1.00 atm at 298 k, would the calcium oxide form spontaneously? Use free energy to answer this.

The vapour pressure of liquid A at 300 K is 76.7 kPa and that of pure liquid B is 52.0 kPa. These two compounds form ideal liquid and gaseous mixtures. Consider the equilibrium composition of a mixture in which the mole fraction of A in the vapour is 0.350. Calculate the total pressure of the vapour and the composition of the liquid mixture.