Answer: The answer is S = 0.1528 cal/g °C
Explanation:
By the law of conservation of energy, energy is neither created nor destroyed.
So, energy lost by metal pieces is equal to the energy gained by water in the calorimeter.
Specific heat of water is 1 cal/g °C
⇒ heat energy Q = mSΔT, where m = mass of a substance
S = specific heat
ΔT = change in temperature
Now, the heat lost by metal piece, Q = 72×S×(96-31)
= 4680×S cal
Heat gained by water, Q = 130×1×(31-25.5)
= 715 cal
⇒ 4680×S = 715.
⇒ S = 0.1528 cal/g °C.
Helium (He) has the lowest melting point of <span>-272.2 °C.</span>
<u>Answer:</u> The
for the reaction is -1406.8 kJ.
<u>Explanation:</u>
Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.
According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.
The chemical reaction for the formation reaction of
is:

The intermediate balanced chemical reaction are:
(1)
( × 6)
(2)
( × 3)
(3)
( × 2)
(4)

The expression for enthalpy of formation of
is,
![\Delta H^o_{formation}=[6\times \Delta H_1]+[3\times \Delta H_2]+[2\times \Delta H_3]+[1\times \Delta H_4]](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Bformation%7D%3D%5B6%5Ctimes%20%5CDelta%20H_1%5D%2B%5B3%5Ctimes%20%5CDelta%20H_2%5D%2B%5B2%5Ctimes%20%5CDelta%20H_3%5D%2B%5B1%5Ctimes%20%5CDelta%20H_4%5D)
Putting values in above equation, we get:
![\Delta H^o_{formation}=[(-74.8\times 6)+(-185\times 3)+(323\times 2)+(-1049\times 1)]=-1406.8kJ](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Bformation%7D%3D%5B%28-74.8%5Ctimes%206%29%2B%28-185%5Ctimes%203%29%2B%28323%5Ctimes%202%29%2B%28-1049%5Ctimes%201%29%5D%3D-1406.8kJ)
Hence, the
for the reaction is -1406.8 kJ.
Answer:
If a substance undergoes a physical change, then it will retain most of its original properties because no new substance is formed.
If a substance undergoes a chemical change, then it will not retain its original properties because a new substance is formed.
Explanation:
So in shorter words its options 2 and 3
Alkenes must undergo addition because they have easily broken tt bonds.
Markonikov's rule states in the addition of HX to an unsymmetrical alkene, the H atom bonds to the less substituted carbon atom.
alkenes are unsaturated hydrocarbons because they have fewer than the maximum number of hydrogen atoms per carbon.
Alkyl halides have good leaving groups and therefore readily undergo substitution and elimination reactions.
In hydroboration, the boron atom bonds to the substituted carbon.
Hydroxides, amines and alcoxides undergo substitution and elimination, but can do so only when the heteroatom is made into a good leaving group.