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? NaOH(s)→NaOH(aq) + kJ NaOH(s)+ kJ →NaOH(aq) NaOH(s)→NaOH(l) + kJ NaOH(aq)→NaOH(s) + kJ NaOH(aq)+ kJ →NaOH(s) NaOH(l)+ kJ → NaOH(s)
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
- 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?
- NaOH(s)→NaOH(aq) + kJ
- NaOH(s)+ kJ →NaOH(aq)
- NaOH(s)→NaOH(l) + kJ
- NaOH(aq)→NaOH(s) + kJ
- NaOH(aq)+ kJ →NaOH(s)
- NaOH(l)+ kJ → NaOH(s)
- What is the definition of the temperature of a substance?
- the speed of the slowest particles in the substance, subtracted from the speed of the fastest particles.
- the heat capacity of the substance times its mass
- a measure of the average kinetic energy of a system
- the total heat content of a substance
- the speed of the fastest particles in the substance
- Which statement describes an endothermic reaction?
- The surroundings warm up.
- The system releases energy.
- The potential energy of the products is less than the potential energy of the reactants.
- The potential energy of the reactants is less than the potential energy of the products.
- Which statement is true regarding the thermochemical equation A + B + KJ àAB
- The reaction is endothermic and produces heat C. The reaction is endothermic and requires heat
- The reaction is exothermic and produces heat. D. The reaction is exothermic and requires heat.
- 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)
- 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?
- This process is endothermic, so the water gets cooler.
- This process is endothermic, so the water gets warmer.
- This process is exothermic, so the water gets cooler.
- This process is exothermic, so the water gets warmer.
- None of the above options can be known for sure.
10.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
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
