Solution of the variant 74 KR №1 - chemisty Shimanovich

The decision of the test No. 1 of option 74 of the collection of chemistry Shimanovich I.E.
(formatted in Microsoft Word)

Tasks:

16. On oxidation of 16.74 g of a divalent metal, 21.54 g of oxide was formed. Calculate the equivalent masses of the metal and its oxide. What are the molar and atomic masses of a metal?

38. Quantum numbers for electrons of the external energy level of atoms of some element have the following meanings: n = 4; l = 0; m1, = 0; ms = ± 0.5. Write the electronic formula for the atom of this element and determine how many free 3d orbitals it contains.

56. Chromium forms compounds in which it exhibits oxidation states +2, +3, +6. Draw up the formulas of its oxides and hydroxides corresponding to these oxidation states. Write the reaction equations proving the amphotericity of chromium (III) hydroxide.

78. Draw the energy diagram of the formation of the O2 molecule by the method of molecular orbitals (MO). How does the MO method explain the paramagnetic properties of an oxygen molecule?

84. When gaseous hydrogen sulfide and carbon dioxide interact, water vapor and carbon disulfide CS2 (g) are formed. Write the thermochemical equation for this reaction by calculating its thermal effect. Answer: +65.43 kJ

119. Calculate at what temperature the dissociation of phosphorus pentachloride will begin, proceeding according to the equation:
PC15 (g) = PC13 (g) + Cl2 (g); H = + 92.59 kJ.
Answer: 509 K.

124. The reaction proceeds according to the equation N2 + 3H2 = 2NH3. The concentrations of the substances involved in it were: [N2] = 0.80 mol / l; [H2] = 1.5 mol / L; [NN3] = 0.10 mol / L. Calculate the concentration of hydrogen and ammonia when [N2] = 0.5 mol / L. Answer: [NH3] = 0.70 mol / l; [H] = 0.60 mol / l.

142. What is the normality of a 30% NaOH solution with a density of 1.328 g / cm3? To 1 liter of this solution was added 5 liters of water. Calculate the percentage of the resulting solution. Answer: 9.96 n .; 6.3%.

161. A solution containing 0.512 g of nonelectrolyte in 100 g of benzene crystallizes at 5.296 ° C. The crystallization temperature of benzene is 5.5 ° C. Cryoscopic constant 5.1 °. Calculate the molar mass of the solute. Answer: 128 g / mol.

184. Which of the substances: Al (OH) 3; H2SO4; Ba (OH) 2 - will interact with potassium hydroxide? Express these reactions with molecular and ionic-molecular equations.

214. When mixing solutions A12 (SO4) 3 and Na2CO3, each of the salts taken is irreversibly hydrolyzed to the end with the formation of the corresponding base and acid. Draw up the ionic-molecular and molecular equations of the ongoing joint hydrolysis.