Which process/es is/are spontaneous? I. rusting fire II. melting of iron III. freezing of water IV. combustion of methane, C. II and III only , D. I and IV only, Which is always positive when a spontaneous process occurs? , D. ΔS universe, A. ΔH universe, What will likely happen to entropy when the reaction is spontaneous?, A. entropy increases , B. entropy decreases, Which statement BEST describes the second law of thermodynamics?, B. The total quantity of energy in the universe stays the same. , A. Processes that involve the transfer or conversion of heat energy are irreversible.  , The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time, and is constant if and only if all processes are reversible. Which BEST explains this statement?, A. All the spontaneous processes result in decreased total entropy of a system., B. All the spontaneous processes result in increased total entropy of a system., One application of the second law of thermodynamics is when we put an ice cube in a cup with water at room temperature. Which of the following will likely happen? , A. The water releases off heat and the ice cube melts. Hence, the entropy of water decreases. , D. The water absorbs heat and the ice cube melts. Hence, the entropy of water increases., Which of the following statements regarding the Gibbs free energy change for a reaction is FALSE? , A. The Gibbs free energy change is the proportion of the enthalpy change of a reaction that is used to increase the entropy., B. If the Gibbs free energy change for a reaction is negative, the reaction happens spontaneously., The Haber Process may be described by the equation: N₂(g) + 3H₂(g) ⇌ 2NH₃(g) What is the equilibrium constant for this process?, A. Kc = [NH₃] / [N₂][H₂], B. Kc = [N₂][H₂]³ / [NH₃], C. Kc = [NH₃]² / [N₂][H₂]³, D. Kc = [N₂][H₂]³ / [NH₃]², A few drops of concentrated sulphuric acid were added to a mixture of 0.1 mol of methanol and 0.2 mol of ethanoic acid. Even after a considerable time, the reaction mixture was found to contain some of each reactant. Which of the following is the BEST explanation for the incomplete reaction?, A. The temperature was too low., B. Insufficient methanol was used., C. Insufficient ethanoic acid was used., D. An equilibrium mixture was formed., The diagram on the right shows the concentrations of hydrogen, iodine and hydrogen iodide for the reaction between hydrogen and iodine. Which of the following statements is INCORRECT?, C. Adding more hydrogen at point D will alter the shape of the graph., D. At point A on the time axis, the concentration of all three gases is zero., When is a system considered in a state of equilibrium? , A. The rate of the forward and reverse reactions are unequal., B. The rates of the forward and reverse reactions are equal., C. The rate of reaction is negligible., D. All reaction stops., What is the CORRECT designation of the chemical equilibrium when a catalyst is used in a chemical reaction? , A. Equilibrium shifts to right, decrease in ΔH value., B. Equilibrium shifts to left, increase in ΔH value., C. No change in equilibrium, no change in ΔH., D. Equilibrium shifts to left, no change in ΔH, In a 1-Liter container, the amount of H₂ is 1 mole, the amount of I₂ is 2 moles & the amount of HI is 2 moles at equilibrium. Below is the balanced chemical equation for this reaction: H₂(g) + I₂(g) ⇌ 2HI(g) What is Kc for this reaction?, C. 2.0 , D. 1.33, The equilibrium constant, Kc is 49 at a fixed temperature. Two moles of hydrogen and two moles of iodine are allowed to reach equilibrium at this temperature. What is the concentration of hydrogen iodide at equilibrium? Refer to the chemical equation in test item no. 17. , D. 1.55, C. 4.2, if NH₃(g) = 1.98 M; O₂(g) = 1.12 M; NO(g) = 3.05 M; H₂O(g) = 2.62 M respectively., A. 1.03 × 10² M, B. 1.10 × 10² M, C. 5.85 × 10² M, D. 7.92 × 10² M, For the synthesis of ammonia at 500°C, N₂(g) + 3H₂(g) ⇌ 2NH₃(g), the equilibrium constant is 6.0 × 10⁻². Predict the direction in which the system will shift to reach equilibrium if [NH₃]₀ = 1.0 × 10² M; [N₂]₀ = ? 1.0 × 10² M; [H₂]₀ = 2.0 × 10⁻³ M., A. Right then left, B. Shift to right , Write the correct expression for Kc for the given reversible reaction at equilibrium. CH₃COOH(aq) + C₂H₅OH(aq) ⇌ CH₃COOC₂H₅(aq) + H₂O(l), A. Kc = [CH₃COOC₂H₅][H₂O] / [CH₃COOH][C₂H₅OH], B. Kc = [CH₃COOC₂H₅] / [CH₃COOH][C₂H₅OH], C. Kc = [CH₃COOH][C₂H₅OH] / [CH₃COOC₂H₅][H₂O], D. Kc = [CH₃COOH][C₂H₅OH] / [CH₃COOC₂H₅], What will happen to the position of equilibrium and the value of the equilibrium constant when the temperature is increased in the following reaction? Br₂(g) + Cl₂(g) ⇌ 2BrCl(g) ΔH = +14 kJ, A. Equilibrium shifts towards the products and the equilibrium constant decreases., B. Equilibrium shifts towards the products and the equilibrium constant decreases., C. Equilibrium shifts towards the reactants and the equilibrium constant decreases., D. Equilibrium shifts towards the reactants and the equilibrium constant increases., Henri Le Châtelier studied equilibrium reactions in industry in the late 19th century. According to Le Châtelier's principle, what effect would an increase in pressure have on the yield of ammonia at equilibrium?, A. It would have no effect on the yield of ammonia., B. There would be a greater yield of ammonia., C. More hydrogen and nitrogen are formed., D. The yield of ammonia would be less., Consider the equilibrium reaction: C₂H₅OH + CH₃COOH ⇌ CH₃COOC₂H₅ + H₂O. What effect will likely occur if a catalyst is added on this reaction?, A. The system reaches equilibrium faster., B. More CH₃COOC₂H₅ is formed., C. More C₂H₅OH is formed., D. Less H₂O is formed., Which change will increase the equilibrium concentration of sulfur trioxide in this reaction? 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) ΔH = negative, A. Decreasing the concentration of oxygen, B. Increasing the temperature, C. Increasing the pressure, D. Using a catalyst, Which one of the following would change the value of the equilibrium constant? , A. changing the temperature , B. adding a catalyst, Which statement BEST describes a Bronsted-Lowry base? , A. An electron-pair acceptor , C. A proton acceptor, What is the conjugate base of the HSO₄⁻(aq) ion?, A. H₂SO₄(aq) , B. SO₄²⁻(aq), Which of the following chemical systems at equilibrium involves water acting as a Bronsted-Lowry acid? , A. SO₄²⁻ + H₃O⁺ ⇌ HSO₄⁻ + H₂O, B. H₂O + HCN ⇌ H₃O⁺ + CN⁻, C. NH₄⁺ + OH⁻ ⇌ NH₃ + H₂O, D. H₂O + C ⇌ H₂ + CO, An unknown substance acts as an acid and as a base depending on the reaction's circumstances. What properties do this unknown substance possess to achieve its role? I. donates electrons when reacting with an acid II. donates its protons when reacting with a base III. accepts electrons when reacting with a base IV. accepts protons when reacting with an acid, C. I and III only , D. II and IV only, Which statement supports water as an amphoteric substance? I. Water acts as a base, releasing H+ ions, when it reacts with an acid stronger than itself. II. Water acts as an acid, releasing OH- ions, when it reacts with a base stronger than itself. III. Under the right conditions, water releases either a free hydrogen ion (H+) or a free hydroxide ion (OH)., A. I only , D. I, II and III, Which is always TRUE at all conditions of temperature and pressure for a sample of pure water? , C. [H₃O⁺] = [OH⁻] , D. pH = 7.0, The pOH of a solution of NaOH is 11.30. What is the [H⁺] for this solution?, A. 2.0 × 10⁻³ , B. 2.5 × 10⁻³ , Which equation can be used to calculate the pH of a solution from the concentration of hydronium ions?, A. pH = [H₃O⁺][OH⁻], B. pH = log[H₃O⁺]², C. pH = -log [H₃O⁺], D. pH = [H₃O⁺]², A student researcher is trying to determine the pH of an unknown solution. He placed phenolphthalein indicator in that solution. The solution turned into a purplish colour. What is likely the pH of the unknown solution?, A. The solution is basic. , B. The solution is neutral. , The concentration of H₃O⁺ in a patient's blood sample is 11.65 × 10⁻⁸ M. Is the blood acidic, basic, or neutral? , A. The solution is strongly basic., B. The solution is strongly acidic., C. The solution is slightly acidic., D. The solution is slightly basic., What is the concentration of OH⁻ ions in the blood for test item no. 36?, A. 8.51 × 10⁻⁸, B. 7.33 × 10⁻⁸, C. 6.93 × 10⁻⁷, D. 4.65 × 10⁻⁷, Refer to the data below for nos. 38–40: The value of Kw at 10°C is 2.95 × 10⁻¹⁵ What is the [H₃O⁺] at this temperature? , C. 5.4 × 10⁻⁸ , D. 6.6 × 10⁻⁸, The value of Kw at 10°C is 2.95 × 10⁻¹⁵. What is the pOH of water at this temperature?, C. 6.6 , D. 7.3, The value of Kw at 10°C is 2.95 × 10⁻¹⁵ What is the pH of water at this temperature? , C. 6.6 , D. 7.3, Refer to the data below for nos. 41–42: Two water molecules are able to react with other forms to form a hydronium ion and a hydroxide ion. This is known as the self-ionization of water. Using the concentrations of ions produced, it is possible to determine the equilibrium constant for the ionization of water, also known as the ion-product constant of water. Which equation represents the ion-product constant of water? , A. Kw = [H₃O⁺][OH⁻], B. Kw = [H₃O⁺]²[OH⁻], C. Kw = [H₃O⁺] + [OH⁻], D. Kw = [H₃O⁺] - [OH⁻], Refer to the data below for nos. 41–42: Two water molecules are able to react with other forms to form a hydronium ion and a hydroxide ion. This is known as the self-ionization of water. Using the concentrations of ions produced, it is possible to determine the equilibrium constant for the ionization of water, also known as the ion-product constant of water. What is the value of Kw if the sample of water has a pH of 7.30?, A. 1.012 × 10⁻⁵, B. 2.512 × 10⁻¹⁴, C. 5.015 × 10⁻¹⁵, D. 5.030 × 10⁻¹⁵, Blood itself tends to be a buffer solution by keeping its pH value constant. Buffer solutions help in the adjustment of the nature of blood. Which of the statements below may CORRECTLY describe the role of buffers in our body? Statement 1: If the alkaline nature of blood increases, buffer solutions tend to increase the pH value of blood. Statement 2: If the blood becomes acidic, buffer solutions increase the pH value of blood., A. Only Statement 1 is correct., B. Only Statement 2 is correct., C. Both statements are correct., D. Neither of the two are correct., The nature of buffers is to maintain the pH of the solution relatively stable. What comprise buffers to attain this? , A. Weak acid and their conjugate base, B. Weak base and their conjugate acid, C. Strong acid and weak base, D. Strong acid and strong base, A buffer solution has a pH of 4.87. If the buffer contains a weak acid (Ka = 3.30 × 10⁻⁵), What is the [conjugate base] / [weak acid] ratio? , A. 0.41 , B. 2.45, Which of the following reaction does NOT involve oxidation – reduction reaction?, A. Zn + 2HCl → ZnCl₂ + H₂, B. CH₄ + O₂ → CO₂ + H₂O, C. 2Na + 2H₂O → 2NaOH + H₂, D. NaOH + HNO₃ → NaNO₃ + H₂O, What will likely occur when a clean iron nail is dipped into a solution of silver nitrate?, A. The iron nail will become silver-plated., B. The iron will be reduced., C. The iron will be oxidized., D. No reaction occurs., For test item nos. 48–52: Diego Laurio, a STEM Grade 11 student is currently observing an experimentation in oxidation-reduction reaction. Below is the unbalanced reaction he noted from the experimentation. K₃Fe(NO₃)₆ + Cr₂O₃ + KOH ⟹ K₂CrO₄ + K₄Fe(NO₃)₆ + H₂O.  How many electrons are lost / gained in the reaction?, A. 10+, B. 6+, For test item nos. 48–52: Diego Laurio, a STEM Grade 11 student is currently observing an experimentation in oxidation-reduction reaction. Below is the unbalanced reaction he noted from the experimentation. K₃Fe(NO₃)₆ + Cr₂O₃ + KOH ⟹ K₂CrO₄ + K₄Fe(NO₃)₆ + H₂O. In the reaction above, which compound (if any) is reduced?  , A. Cr₂O₃ , B. K₃Fe(NO₃)₆ , For test item nos. 48–52: Diego Laurio, a STEM Grade 11 student is currently observing an experimentation in oxidation-reduction reaction. Below is the unbalanced reaction he noted from the experimentation. K₃Fe(NO₃)₆ + Cr₂O₃ + KOH ⟹ K₂CrO₄ + K₄Fe(NO₃)₆ + H₂O.  Which compound is the reducing agent?  , A. Cr₂O₃ , B. K₂CrO₄ , For test item nos. 48–52: Diego Laurio, a STEM Grade 11 student is currently observing an experimentation in oxidation-reduction reaction. Below is the unbalanced reaction he noted from the experimentation. K₃Fe(NO₃)₆ + Cr₂O₃ + KOH ⟹ K₂CrO₄ + K₄Fe(NO₃)₆ + H₂O. Which of the following is the correct balanced equation?  , A. 2e⁻ + 2K₃Fe(NO₃)₆ + Cr₂O₃ + 10KOH → 2K₂CrO₄ + 2K₄Fe(NO₃)₆ + 5H₂O + 2e⁻, B. 3e⁻ + 3K₃Fe(NO₃)₆ + Cr₂O₃ + 10KOH → 2K₂CrO₄ + 3K₄Fe(NO₃)₆ + 5H₂O + 3e⁻, C. 6e⁻ + 6K₃Fe(NO₃)₆ + Cr₂O₃ + 10KOH → 2K₂CrO₄ + 6K₄Fe(NO₃)₆ + 5H₂O + 6e⁻, D. 10e⁻ + 10K₃Fe(NO₃)₆ + Cr₂O₃ + 10KOH → 2K₂CrO₄ + 10K₄Fe(NO₃)₆ + 5H₂O + 10e⁻, Nitrogen has the same oxidation number in all of the following except , C. NH₄Cl, D. Ca(NO₃)₂, The figure on the right represents an electrolytic cell. Which of the following statements is TRUE about ELECTROLYTIC cells?, A. Electrons flow from the cathode to the anode in the external circuit., B. The redox reaction involved in such a cell is spontaneous., C. Oxidation occurs at the cathode., D. Reduction occurs at the cathode., For nos. 54–55, refer to the data below: An electrochemical cell is constructed using electrodes based on the following half reactions: Ni(s) → Ni²⁺(aq) + 2e⁻ E°= -0.257V Au³⁺(aq) + 3e⁻ → Au(s) E°= +1.498V Which is the cathode and anode in this cell respectively? , C. Ni, Au²⁺ , B. Au²⁺, Ni, Ni(s) → Ni²⁺(aq) + 2e⁻ E°= -0.257V Au³⁺(aq) + 3e⁻ → Au(s) E°= +1.498V What is the standard cell potential?, A. +1.755 V , B. -1.755 V, The E° value of Ni2+/Ni is -0.25V and Ag+/Ag is +0.80V. If a cell is made by taking the two electrodes, what is the feasibility of the reaction? , A. Since E° value for the cell will be negative, redox reaction is not feasible., B. Since E° value for the cell will be positive, redox reaction is feasible., C. Ni cannot reduce Ag⁺ to Ag hence reaction is not feasible., D. Ag can reduce Ni²⁺ hence reaction is feasible., The following statements are sequentially arranged to show how lead acid batteries work. Which among these steps are CORRECTLY stated? I. A lead acid battery consists of a negative electrode made of spongy or porous lead. The lead is porous to facilitate the formation and dissolution of lead. The positive electrode consists of lead oxide. II. One of the electrodes is immersed in an electrolytic solution of sulfuric acid and water. III. The sulphate within the acetic acid bonds to the lead. IV. The chemical reaction causes the battery to produce electricity., A. I and II only , B. II and III only, Corrosion is a reduction-oxidation reaction in which the metal is being oxidized by its surroundings. As the lead acid battery runs, the sulfuric acid releases hydrogen gas. The gas then mixes with the air around it. The chemical reaction that takes place as hydrogen gas collides with the air, moisture and salt causes corrosion. What are the preventive measures to slow down this phenomenon? I. Coat your battery terminals with dielectric grease or battery terminal protector. II. Make sure the battery is stored in a moderate temperature environment. III. Undercharging or overcharging can extend the life span of the battery. IV. Check for leaking fluids., C. I, II and III only , D. I, II and IV only, The reaction below shows the electrolysis of water. Which statements correctly describe the information below? oxidation (anode): 2H₂O(l) → O₂(g) + 4H⁺(aq) + 4e⁻ E° = -1.23 V reduction (cathode): 2H₂O(l) + 2e⁻ → H₂(g) + 2OH⁻(aq) E° = -0.83 V overall reaction: 2H₂O(l) → O₂(g) + 2H₂(g) E°cell = -2.06 V I. The electrolysis of water produces hydrogen and oxygen gases. II. At the anode, water is reduced to hydrogen gas and hydroxide ions. III. At the cathode, water is oxidized to oxygen gas and hydrogen ions., A. I only , B. II and III only, The electrolytic process is widely used in various industrial applications. One major application of this process is the extraction of pure metal from their ores (Electro-extraction). Below is a series of steps on how to conduct electro-extraction. Which one is NOT included?, A. the metal ore is treated with strong acid, B. the resulting solution is heated, C. the solution is decomposed, D. pure metal is deposited on the cathode..

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