Answer:
527.184 J of heat is removed from a 21 g water sample if it is cooled from 34.0 ° C to 28.0 ° C.
Explanation:
Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.
When the heat added or removed from a substance causes a change in temperature in it, this heat is called sensible heat.
In other words, the sensible heat of a body is the amount of heat received or transferred by a body when it undergoes a change in temperature without there being a change in physical state (solid, liquid or gaseous). The equation that allows to calculate this heat exchange is:
Q = c * m * ΔT
Where Q is the heat exchanged by a body of mass m, constituted by a substance of specific heat c and where ΔT=Tfinal-Tinitial is the change in temperature.
In this case:
- c= 4.184
- m=21 g
- ΔT=Tfinal-Tinitial=28 °C - 34 °C=-6 °C
Replacing:
Q= 4.184 * 21 g* (-6 C)
Q= - 527.184 J
To lower the temperature, heat has to be given, for that the final temperature must be lower than the initial temperature; and it receives the name of transferred heat and has a negative value, as in this case.
<u><em>
527.184 J of heat is removed from a 21 g water sample if it is cooled from 34.0 ° C to 28.0 ° C.</em></u>
Based on atomic mass
Explanation:
Elements were arranged on the first periodic table based on their atomic masses.
The mass of an atom is made up of the mass of the nucleus which contains the protons and neutrons.
- Dimitri Mendeleev was the first person credited for arranging elements periodically.
- He was said to have been inspired while playing his game of solitaire on a train.
- On his table, he left spaces for the atomic masses of elements not yet discovered.
- Today, the periodic table is based on the atomic numbers of elements. This is the number of protons in an atom.
Learn more:
Periodic table brainly.com/question/2690837
#learnwithBrainly
Answer:
Rate = k . [B]² . [C]
Explanation:
The dependence of the reaction rate on the concentration of the reactants is given by the reaction order of each one, as shown in the rate equation.
![Rate=k.[A]^{x} .[B]^{y} .[C]^{z}](https://tex.z-dn.net/?f=Rate%3Dk.%5BA%5D%5E%7Bx%7D%20.%5BB%5D%5E%7By%7D%20.%5BC%5D%5E%7Bz%7D)
where,
k is the rate constant
x, y, z are the reaction orders.
- <em>The rate of reaction is not affected by changing the concentration of species A.</em> This means that the reaction order for A is x = 0 since when its concentration changes, the rate stays the same.
- <em>Leaving all other factors identical, doubling the concentration of species B increases the rate by a factor of 4.</em> This means that the reaction order for B is y = 2, so when the concentration is doubled, the new rate is 2² = 4 times the initial rate.
- The rate of the reaction is linearly dependent on the concentration of C. This means that the reaction order for C is z = 1, that is, a linear dependence.
All in all, the rate equation is:
Rate = k . [B]² . [C]
Answer:
Explanation:
Molal freezing point depression constant of butanol Kf = 8.37⁰C /m
ΔTf = Kf x m , m is no of moles of solute per kg of solvent .
mol weight of butanol = 70 g
235.1 g of butanol = 235.1 / 70 = 3.3585 moles
3.3585 moles of butanol dissolved in 4.14 kg of water .
ΔTf = 8.37 x 3.3585 / 4.14
= 6.79⁰C
Depression in freezing point = 6.79
freezing point of solution = - 6.79⁰C .
