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Questions in chemistry

[Terjawab] Constants for water |$\Delta H _{\text {vap }}$ | $40.65 kJ / mol$ | |---|---| |$\Delta H _{ f }$ | $-285.83 kJ / mol$ | |$\Delta H _{\text {fusion }}$ | $6.03 kJ / mol$ | | specific heat | $4.186 J / g ^{\circ} C$ | | molar mass | 18.02 g | How much energy is consumed by thawing 4.3 g ice? A. $4.3 g \times 1 mol / 18.02 g \times 40.65 kJ / mol$ B. $4.3 g \times 1 mol / 18.02 g \times 4.186 kJ / mol$ C. $4.3 g \times 1 mol / 18.02 g \times 6.03 kJ / mol$ D. $4.3 g \times 1 mol / 18.02 g \times(-285.83) kJ / mol$

[Terjawab] Based on the information in the table, which two elements are most likely in the same group, and why? | Element | Atomic mass (amu) | Total electrons | Valence electrons | Year isolated | |---|---|---|---|---| | Bismuth (Bi) | 209 | 83 | 5 | 1753 | | Nitrogen (N) | 14 | 7 | 5 | 1772 | | Oxygen (O) | 16 | 8 | 6 | 1772 | | Sodium (Na) | 23 | 11 | 1 | 1807 | | Thallium (TI) | 204 | 81 | 3 | 1861 | A. bismuth and thallium, because their atomic masses are very similar B. nitrogen and oxygen, because they were both first isolated in the same year C. sodium and thallium, because their names both end in the same suffix: -ium D. bismuth and nitrogen, because they have the same number of valence electrons

[Terjawab] Which of the following ions exhibits the highest magnetic moment? (a) Fe²⁺ (b) Mn²⁺ (c) Cu²⁺ (d) Co²⁺

[Terjawab] Table 1 shows the electron arrangement for elements W, X, Y, and Z. | Element | Electron Arrangement | |---------|---------------------| | W | 2.4 | | X | 2.8 | | Y | 2.8.2 | | Z | 2.8.7 | Which element is a metal? A) W B) X C) Y D) Z

[Terjawab] The following process shows two changes: H₂O at 0°C -> H₂O at 25°C -> H₂O at 100°C Identify process X and Y. a) X - Freezing, Y - Melting b) X - Melting, Y - Boiling c) X - Condensation, Y - Melting d) X - Evaporation, Y - Condensation

[Terjawab] Which acids have hydro- as part of their name? H₂SO₃ HBr HClO₂ HF HNO₃

[Terjawab] A gaseous reaction 2X(g) → Y(g) is observed to be second order with respect to reactant X. If the half-life of this reaction is 20 minutes when the initial partial pressure of X is 0.4 atm, what will be the half-life when the initial partial pressure of X is increased to 0.8 atm, assuming the temperature remains constant? (A) 5 minutes (B) 10 minutes (C) 20 minutes (D) 40 minutes

[Terjawab] Consider the chemical equilibrium of a soap that is present in its aqueous solution. [tex]\begin{array}{c} C_{17} H_{35} COONa(aq) \\ \text { sodium stearate (soap) } \end{array} \Leftrightarrow C_{17} H_{35} COO^{-}(aq)+Na^{+}(aq)+\begin{array}{l} \text { stearate ion } \end{array}[/tex] What will happen if a large quantity of NaCl is added to the aqueous solution? A. The equilibrium will shift to the right, favoring the dissociation of soap in aqueous solution. B. The equilibrium will shift to the left to such an extent that it leads to the precipitation of solid soap. C. The equilibrium will not be affected by the addition of NaCl to the solution. D. The equilibrium will be permanently destroyed by the addition of NaCl.

[Terjawab] What is the pOH of a solution with $[OH^{-}]=1.4 \times 10^{-18}$? A. 13.15 B. 12.85 C. -13.15 D. 14.00

[Terjawab] i. Write a balanced chemical equation of Calcium oxide in water: [tex]CaO (s)+ H _2 O (1) \rightarrow Ca (OH)_2[/tex] ii. What is the common name for Calcium Oxide? iii. During production of calcium oxide from limestone, a gas is evolved as a byproduct. Describe the chemical test for the gas and by what method is the gas collected/prepared in the laboratory? Give a reason for your answer.