Which statement is true regarding the thermochemical equation A + B + KJ à AB A. The reaction is endothermic and produces heat C. The reaction is endothermic and requires heat B. The reaction is exothermic and produces heat. D. The reaction is exothermic and requires heat. 8 150.0 mL of water releases 7.84 kJ of energy. The specific heat capacity of water is 4.184 J/g·°C. What is the temperature change? (1mL of water = 1 g) A. 3.52oC B. -12.5 °C C. - 0.0125oC D. 0.0125°C E. 12.5°C 9 When a sample of potassium nitrate is dissolved in water, the temperature of the water changes from 18.5°C to 20.3°C. Which statement describes this process of the change of state of potassium nitrate? A. This process is endothermic, so the water gets cooler. B. This process is endothermic, so the water gets warmer. C. This process is exothermic, so the water gets cooler. D. This process is exothermic, so the water gets warmer. E. None of the above options can be known for sure.
States of Matter
The substance that constitutes everything in the universe is known as matter. Matter comprises atoms which in turn are composed of electrons, protons, and neutrons. Different atoms combine together to give rise to molecules that act as a foundation for all kinds of substances. There are five states of matter based on their energies of attraction, namely solid, liquid, gases, plasma, and BEC (Bose-Einstein condensates).
Chemical Reactions and Equations
When a chemical species is transformed into another chemical species it is said to have undergone a chemical reaction. It consists of breaking existing bonds and forming new bonds by changing the position of electrons. These reactions are best explained using a chemical equation.
Just solve questions 7-10, thanks.
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What is the symbol for the enthalpy change that occurs during the phase change of a substance from solid to liquid? A. ∆H°melt B. ∆H°fre C. ∆H°boil D. ∆H°vap E. ∆H°cond |
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You are building an ice skating rink and want to select flooring that experiences the least amount of temperature shift under changing conditions. Which substance would be least suitable, based on specific heat cap.? A. aluminum B. concrete C. granite D. wood |
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5.0 g of argon gas is condensed. How much energy is transferred? A. 0.16 kJ B. 0.79 kJ C. -0.16 kJ D. -0.79 kJ |
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5.50 g of solid sodium hydroxide is dissolved in 175 mL of water. Using a coffee-cup calorimeter, the temperature change of the water is measured to be -2.1°C. Which equation best describes this system? A. NaOH(s) → NaOH(aq) + kJ C. NaOH(s) + kJ →NaOH(aq) E. NaOH(s) → NaOH(l) + kJ B. NaOH(aq) → NaOH(s) + kJ D. NaOH(aq) + kJ → NaOH(s) F. NaOH(l) + kJ → NaOH(s) |
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What is the definition of the temperature of a substance? A. the speed of the slowest particles in the substance, subtracted from the speed of the fastest particles. B. the heat capacity of the substance times its mass C. a measure of the average kinetic energy of a system D. the total heat content of a substance E. the speed of the fastest particles in the substance |
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Which statement describes an endothermic reaction? A. The surroundings warm up. B. The system releases energy. C. The potential energy of the products is less than the potential energy of the reactants. D. The potential energy of the reactants is less than the potential energy of the products. |
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Which statement is true regarding the thermochemical equation A + B + KJ à AB A. The reaction is endothermic and produces heat C. The reaction is endothermic and requires heat B. The reaction is exothermic and produces heat. D. The reaction is exothermic and requires heat. |
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150.0 mL of water releases 7.84 kJ of energy. The specific heat capacity of water is 4.184 J/g·°C. What is the temperature change? (1mL of water = 1 g) A. 3.52oC B. -12.5 °C C. - 0.0125oC D. 0.0125°C E. 12.5°C |
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When a sample of potassium nitrate is dissolved in water, the temperature of the water changes from 18.5°C to 20.3°C. Which statement describes this process of the change of state of potassium nitrate? A. This process is endothermic, so the water gets cooler. B. This process is endothermic, so the water gets warmer. C. This process is exothermic, so the water gets cooler. D. This process is exothermic, so the water gets warmer. E. None of the above options can be known for sure. |
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A ring with a mass of 14.8g is tossed into a fire and then removed. The ring’s temperature went from 23.2oC to 55.8oC. During this process, the ring gained 214J of heat. Of what pure metal is the ring composed? A. copper B. iron C. gold D. aluminum |
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