Answer:
Explanation:
We are asked to find how many kilojoules of energy would be required to heat a block of aluminum.
We will use the following formula to calculate heat energy.
The mass (m) of the aluminum block is 225 grams and the specific heat (c) is 0.897 Joules per gram degree Celsius. The change in temperature (ΔT) is the difference between the final temperature and the initial temperature.
- ΔT = final temperature - inital temperature
The aluminum block was heated from 23.0 °C to 73.5 °C.
- ΔT= 73.5 °C - 23.0 °C = 50.5 °C
Now we know all three variables and can substitute them into the formula.
- m= 225 g
- c= 0.897 J/g° C
- ΔT= 50.5 °C
Multiply the first two numbers. The units of grams cancel.
Multiply again. This time, the units of degrees Celsius cancel.
The answer asks for the energy in kilojoules, so we must convert our answer. Remember that 1 kilojoule contains 1000 joules.
Multiply by the answer we found in Joules.
The original values of mass, temperature, and specific heat all have 3 significant figures, so our answer must have the same. For the number we found, that is the tneths place. The 9 in the hundredth place tells us to round the 1 up to a 2.
Approximately <u>10.2 kilojoules</u> of energy would be required.
Answer:
The metal has a heat capacity of 0.385 J/g°C
This metal is copper.
Explanation:
<u>Step 1</u>: Data given
Mass of the metal = 21 grams
Volume of water = 100 mL
⇒ mass of water = density * volume = 1g/mL * 100 mL = 100 grams
Initial temperature of metal = 122.5 °C
Initial temperature of water = 17°C
Final temperature of water and the metal = 19 °C
Heat capacity of water = 4.184 J/g°C
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<u>Step 2: </u>Calculate the specific heat capacity
Heat lost by the metal = heat won by water
Qmetal = -Qwater
Q = m*c*ΔT
m(metal) * c(metal) * ΔT(metal) = - m(water) * c(water) * ΔT(water)
21 grams * c(metal) *(19-122.5) = -100 * 4.184 * (19-17)
-2173.5 *c(metal) = -836.8
c(metal) = 0.385 J/g°C
The metal has a heat capacity of 0.385 J/g°C
This metal is copper.
Answer:
e) The activation energy of the reverse reaction is greater than that of the forward reaction.
Explanation:
- Activation energy is the minimum amount of energy that is required by the reactants to start a reaction.
- An exothermic reaction is a reaction that releases heat energy to the surrounding while an endothermic reactions is a reaction that absorbs heat from the surrounding.
- <em><u>In reversible reactions, when the forward reaction is exothermic it means the reverse reaction will be endothermic, therefore the reverse reaction will have a higher activation energy than the forward reaction.</u></em> The activation energy of the reverse reaction will be the sum of the enthalpy and the activation energy of the forward reaction.
2 valence electrons
Explanation:
Most transition metals have 2 valence electrons. Valence electrons are the sum total of all the electrons in the highest energy level (principal quantum number n). Most transition metals have an electron configuration that is ns2(n−1)d , so those ns2 electrons are the valence electrons.
