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How are chemical equations typically written?
- A. Products → Reactants
- B. Reactants → Products
- C. Reactants + Reactants
- D. Products + Reactants
Correct Answer: B
Rationale: Chemical equations are typically written with reactants listed on the left side of the arrow and products on the right side. This convention signifies the progression of reactants transforming into products during a chemical reaction. Therefore, the correct way chemical equations are typically written is 'Reactants Ć’ Products.'
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When propane is reacted in the presence of oxygen gas, the products of this combustion reaction are:
- A. C + H2
- B. CH2 + H2O
- C. CO2 + H2
- D. CO2 + H2O
Correct Answer: D
Rationale: When propane undergoes combustion in the presence of oxygen, it forms carbon dioxide (CO2) and water (H2O). The balanced chemical equation for this reaction is: C3H8 + 5O2 -> 3CO2 + 4H2O. This means that three molecules of carbon dioxide and four molecules of water are produced when one molecule of propane reacts with five molecules of oxygen. Therefore, option D (CO2 + H2O) is the correct answer.
Identify the reactants in the chemical reaction below: CH₄ + 2O₂ → CO₂ + 2H₂O
- A. CHâ‚„ and Oâ‚‚
- B. COâ‚‚ and Hâ‚‚O
- C. Both
- D. None of the above
Correct Answer: A
Rationale: Reactants in a chemical reaction are the initial substances that are transformed into products. In this reaction, CHâ‚„ (methane) and Oâ‚‚ (oxygen) are the reactants, as they are the starting materials that undergo a chemical change to form COâ‚‚ (carbon dioxide) and 2Hâ‚‚O (water). The equation clearly shows that CHâ‚„ and Oâ‚‚ are on the left side of the reaction arrow, indicating that they are the reactants. Therefore, the correct answer is A: CHâ‚„ and Oâ‚‚.
What is the density of carbon tetrachloride if a flask weighing 345.8 g is filled with 225 mL of the liquid, and the total weight of the flask and liquid is 703.55 g?
- A. 1.59 g/mL
- B. 2.76 g/mL
- C. 1.4 g/mL
- D. None of the above
Correct Answer: A
Rationale: To find the density of carbon tetrachloride, we first need to determine the weight of the liquid only. The weight of the liquid can be calculated by subtracting the weight of the empty flask from the total weight of the flask and liquid: 703.55 g - 345.8 g = 357.75 g. Now, using the volume of the liquid (225 mL) and its weight (357.75 g), we can calculate the density: Density = Mass/Volume = 357.75 g / 225 mL ĉ� 1.59 g/mL. Therefore, the correct answer is A, 1.59 g/mL.
What is the term for the reactant that is entirely consumed in a reaction?
- A. limiting reactant
- B. reducing agent
- C. reaction intermediate
- D. reagent
Correct Answer: A
Rationale: The term for the reactant that is entirely consumed in a reaction is the limiting reactant. The limiting reactant is crucial in determining the maximum amount of product that can be formed as it is fully consumed in the reaction. The other choices, reducing agent, reaction intermediate, and reagent, do not specifically refer to the reactant that is completely consumed during the reaction process. Identifying the limiting reactant is essential for calculating the theoretical yield of a reaction and understanding the stoichiometry of the reaction.
In an experiment, a student tests three unknown fluids with the following measurements: Fluid A: m=2060g, V=2000mL, Fluid B: m=672g, V=850mL, and Fluid C: m=990g, V=1100mL. Arrange the liquids in the correct order of how they would separate in a beaker from bottom to top.
- A. A, B, C
- B. B, C, A
- C. C, A, B
- D. B, A, C
Correct Answer: B
Rationale: To determine the order in which the liquids will separate in a beaker, we must consider their densities, calculated using the formula Density = Mass (m) / Volume (V). The liquid with the higher density will settle at the bottom, while the liquid with the lower density will rise to the top. For the given fluids, Fluid A has a density of 1.03 g/mL (2060 g / 2000 mL), Fluid B has a density of approximately 0.79 g/mL (672 g / 850 mL), and Fluid C has a density of approximately 0.90 g/mL (990 g / 1100 mL). Based on these calculations, the correct order of the fluids from bottom to top, according to increasing density, is Fluid B, Fluid C, and Fluid A.