Chemistry Answers

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The initial concentration of 1.8 *10³moldm^-3 was found to be 85% complete after 7.5 minutes. What is the final concentration of the reacting system if the total time of the reaction was 11minutes?

The rate constant k= 3.6*10⁷dm^-3mol^-1 at 298k for the second order reaction of two gaseous pollutant

NO+O₃- NO₂+O₂

If the initial concentration of the reactants is 0.15gdm^-1 , what is the final concentration?

The molar solubility of silver chromate, Ag2CrO4, in water at a certain temperature is 6.2 × 10-5 M. What is Ksp for Ag2CrO4 at this temperature?

Which of the following situations will produce a precipitate?

A. A 500 mL solution containing 9.0 × 10^-4 mol Sr²⁺ and 1.0 × 10^-4 mol HPO₄^2- (K_sp for the possible SrHPO₄ = 1.2 × 10^-7).

B. A solution containing 1.2 × 10^-3 M Ba²⁺ and 1.2 × 10^-2 M F^- (K_sp for the possible BaF₂ = 1.8 × 10^-7).

C. A solution containing 0.0030 M Ca²⁺ and 0.025 M CrO₄^2- (K_sp for the possible CaCrO₄ = 7.1 × 10^-4).

D. A solution containing 0.095 M Tl⁺ (thallium(I)) and 0.0020 M Cl^- (K_sp for the possible TlCl = 1.9 × 10^-4).

A container holds 5gms of ccl4 vapour, calculate the number of moles of ccl4 present

1. Saponification of fats needs a strong___to proceed to completion.

A. Halogen

B. Catalyst

C. Acid

D. Base

2. Which of the following elements can onlu form one bond (alkene) in a lewis structure?

A. Oxygen

B. Carbon

C. Hydrogen

D. Aluminum

3. Which element will have 18 electrons in its lewis dot symbol?

A. Argon

B. Boron

C. Carbon

D. Phosphorus

4. Which of the orbitals has the highest energy

A. 1s

B. 2s

C. 2p

D. 3s

5. Short chain alkenes are prepared through___

A. Saponification

B. Hydration

C. Catalytic cracking

D. Oxidation

6. This type of isomerism occurs when different compounds are formed due to the different arrangements of their atoms leading to different functional groups.

A. Chain

B. Functional

C. Positional

D. Geometric

7. Which of the following represents a non-polar covalent bond?

A. Hydrogen-Oxygen

B. Carbon-Nitrogen

C. Carbon-Carbon

D. Lithium-Fluorine

8. Which one of the formulas for ionic compounds below is incorrect?

A. SrCl₂

B. AICH

C. AbP₂

D. CS2S

A piece of metal with a mass of 97.6 grams was heated in a steam jacket to 94°C and then

plunged into 243.6 grams of water at 21 degrees * C causing the temperature to rise to 24 degrees * C What

is the specific heat of metal?

A 0.50 g sample of a Group 2 metal, M, was added to 40.0 cm3 of 1.00 mol dm–3 hydrochloric acid (an excess).

equation 1 M(s) + 2HCl (aq) → MCl 2(aq) + H2(g)

When the reaction had finished, the resulting solution was made up to 100 cm3 in a volumetric flask.

A 10.0 cm3 sample of the solution from the volumetric flask required 15.0 cm3 of 0.050 mol dm–3 sodium carbonate solution, Na2CO3, for complete neutralisation of the remaining hydrochloric acid.

Calculate the total amount, in moles, of hydrochloric acid remaining after the reaction shown in equation 1.

amount = ... mol

Use your answers to (a) and (b)(iv) to calculate the amount, in moles, of hydrochloric acid

that reacted with the 0.50 g sample of M.

amount = ... mol

Use your answer to (v) and equation 1 to calculate the amount, in moles, of M in the 0.50 g sample.

amount = ... mol Calculate the relative atomic mass, Ar, of M and identify M.

Ar of M = ... identity of M = ...

An ice cube of mass 65 g is taken from a freezer at - 15 degrees * C and dropped into 125 cm ^ 3 of water at 85 degrees * C What will be the final temperature of the mixture? The specific heat of ice is 0.5 cal/g.^ C and latent heat of fusion of ice is 80 cal/g.