Chem Lab ACCURATE TESTED VERSIONS OF THE EXAM FROM 2025 TO 2026 | ACCURATE AND VERIFIED ANSWERS | NEXT GEN FORMAT | GUARANTEED PASS

Why does adding water result in a relatively small temperature change? A. Water molecules are heavy B. Water boils quickly C. Water has a high specific heat capacity D. Water reflects heat Correct answer: C. Water has a high specific heat capacity Rationale: Water resists temperature change due to its ability to absorb large amounts of heat without a significant temperature increase. What factors does the transfer of heat depend on? A. Volume, density, and altitude B. Temperature, mass, and substance C. Pressure, color, and shape D. Speed, weight, and area Correct answer: B. Temperature, mass, and substance Rationale: Heat transfer depends on the temperature difference, the mass involved, and the type of substance, which influences specific heat capacity. What’s the purpose of using polystyrene cups? A. To stir solutions easily B. To add mass to the experiment C. They act as an insulated container to prevent heat loss D. To allow faster reaction rates Correct answer: C. They act as an insulated container to prevent heat loss Rationale: Polystyrene is an insulator, reducing heat exchange with the environment and increasing accuracy in calorimetry. How do you calibrate a temperature probe? A. Heat it in boiling water B. Compare with a digital thermometer C. Place it in an ice bath and stir until it stabilizes at 0°C D. Leave it in the sun for 10 minutes Correct answer: C. Place it in an ice bath and stir until it stabilizes at 0°C Rationale: Ice-water baths are a standard calibration method because they provide a consistent 0°C environment. How much heat is transferred if 1,000 g of water is raised 1°C? A. 100 J B. 1,000 J C. 4.197 J D. 4,197 J Correct answer: D. 4,197 J Rationale: The specific heat of water is 4.197 J/g°C, so 1,000 g × 1°C = 4,197 J. In the Heat Capacity experiment, when metal comes in contact with water in the calorimeter what happens? A. The metal absorbs heat from water B. Water evaporates C. The temperature of the metal decreases and provides heat to the water D. Nothing changes Correct answer: C. The temperature of the metal decreases and provides heat to the water Rationale: Heat flows from the hotter metal to the cooler water until thermal equilibrium is reached. When a hot metal comes in contact with room temperature water, what happens to the temperature of the water? A. It stays the same B. It boils rapidly C. It will rise, but not significantly because of its high specific heat D. It cools down Correct answer: C. It will rise, but not significantly because of its high specific heat Rationale: Water’s high specific heat means it absorbs heat slowly, leading to only a moderate temperature increase. Specific heat capacity A. Energy needed to melt a substance B. The boiling point of a substance C. The amount of heat required to change the temperature of 1 gram of a substance 1°C D. The ability to conduct electricity Correct answer: C. The amount of heat required to change the temperature of 1 gram of a substance 1°C Rationale: Specific heat is defined as energy per unit mass per degree change in temperature. What is the balanced equation for the synthesis of malachite? A. CuSO4 + Na2CO3 → CuCO3 + Na2SO4 B. Cu + CO2 + H2O → CuCO3 C. 2CuSO4 + H2O + 2Na2CO3 → Cu2CO3(OH)2 + 2Na2SO4 + CO2 + 9H2O D. CuSO4 + 2NaOH → Cu(OH)2 + Na2SO4 Correct answer: C. 2CuSO4 + H2O + 2Na2CO3 → Cu2CO3(OH)2 + 2Na2SO4 + CO2 + 9H2O Rationale: This is the full balanced equation for the reaction producing malachite. What should you look for when determining the equation for malachite? A. Presence of CO2 B. 9H2O as a product C. NaOH as a reactant D. CuO as a product Correct answer: B. 9H2O as a product Rationale: The formation of malachite in this reaction includes water as a byproduct—specifically 9 molecules. What is the excess reagent in the synthesis of malachite? A. CuSO4 B. Water C. Carbon dioxide D. Sodium carbonate Correct answer: D. Sodium carbonate Rationale: Sodium carbonate is present in excess to ensure complete reaction with CuSO4. What is the limiting reagent in the synthesis of verdigris? A. Na2CO3 B. H2O C. CuSO4 D. CO2 Correct answer: C. CuSO4 Rationale: The limiting reagent is the one that gets used up first—in this case, CuSO4. What is the mole to mole ratio of copper sulfate to malachite? A. 1:2 B. 2:1 C. 1:1 D. 3:2 Correct answer: B. 2:1 Rationale: Two moles of CuSO4 are needed to form one mole of malachite. What should you do if ammonia gets in your eyes? A. Close eyes tightly B. Blink several times C. Rinse with water for at least 15 minutes and seek medical attention D. Rub your eyes with a tissue Correct answer: C. Rinse with water for at least 15 minutes and seek medical attention Rationale: Ammonia is caustic, and prolonged rinsing is essential to reduce damage. If CuSO4·5H2O is spilled on your hands, what should you do? A. Wipe it with a towel B. Use hand sanitizer C. Wash hands with water and non-abrasive soap D. Scrape it off Correct answer: C. Wash hands with water and non-abrasive soap Rationale: Gentle cleaning prevents irritation and further chemical exposure. Is filter paper required for a Büchner funnel? A. No B. Yes C. Only for hot liquids D. Only for small volumes Correct answer: B. Yes Rationale: Filter paper is essential to separate solids from liquids during vacuum filtration. What produces the bubbles in the synthesis of malachite? A. Oxygen B. Boiling water C. Evolution of carbon dioxide D. Hydrogen gas Correct answer: C. Evolution of carbon dioxide Rationale: CO2 is released as a byproduct of the reaction, forming visible bubbles. Should you pour chemicals down the sink? A. Yes, if diluted B. Only water C. No, pour them into the hazardous waste compartment D. Only organic solvents Correct answer: C. No, pour them into the hazardous waste compartment Rationale: Improper disposal can harm the environment and violate lab safety protocols. Which filtration requires the water aspirator? A. Gravity filtration B. Paper filtration C. Vacuum filtration D. Centrifugation Correct answer: C. Vacuum filtration Rationale: The aspirator generates suction to speed up filtration in a Büchner funnel setup What determines the percentage of natural cranberry juice in cranberry apple juice? A. Taste test B. UV Spectrophotometer C. Color chart D. Litmus paper Correct answer: B. UV Spectrophotometer Rationale: The UV Spectrophotometer measures light absorbance, which correlates to concentration of cranberry compounds. How does the UV-Vis Spectrophotometer work? A. By measuring pH of the solution B. Involves light reflection from the surface C. Involves the interaction between electromagnetic radiation with matter, measures the intensity of transmitted light, and finds the degree of absorbance D. By boiling the solution and measuring vapor Correct answer: C. Involves the interaction between electromagnetic radiation with matter, measures the intensity of transmitted light, and finds the degree of absorbance Rationale: UV-Vis Spectroscopy is based on how much light a substance absorbs at specific wavelengths. How are the units for absorbance and wavelength for cranberry juice? A. Grams and millimeters B. No units and micrometers C. Visible range and nanometers D. Molarity and seconds Correct answer: C. Visible range and nanometers Rationale: Absorbance is unitless; wavelength is measured in nanometers within the visible light spectrum. In the cranberry experiment, what were the units of the x and y axis? A. Time and temperature B. pH and voltage C. Concentration (x) and absorbance (y) D. Mass (x) and volume (y) Correct answer: C. Concentration (x) and absorbance (y) Rationale: This is standard in Beer-Lambert Law plots for UV-Vis analysis. What gives cranberries their dark red color? A. Tannins B. Anthocyanin C. Carotene D. Citric acid Correct answer: B. Anthocyanin Rationale: Anthocyanins are red-violet pigments found in cranberries and other berries. What terms are associated with MS (Mass Spectrometry)? A. pKa and titration B. Molecular ion, fragment ion, mass of ion C. Wavelength and absorbance D. Specific heat and molarity Correct answer: B. Molecular ion, fragment ion, mass of ion Rationale: These terms relate to how molecules are ionized and fragmented in MS analysis. What terms are used with Chromatography? A. Flame and burner B. Acid and base C. Mobile phase, stationary phase D. Solubility and filtration Correct answer: C. Mobile phase, stationary phase Rationale: Chromatography separates components based on their interaction with these two phases. What is the inert gas in experiment 11 (GC-MS)? A. Nitrogen B. Oxygen C. Helium D. Hydrogen Correct answer: C. Helium Rationale: Helium is an inert carrier gas commonly used in Gas ChromatographyMass Spectrometry.