Answer: II. The catalyst provides a new pathway in the reaction mechanism.
III. The catalyst speeds up the reaction.
Explanation:
Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.
A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and more molecules convert to products.
The catalyst itself does not take part in the chemical reaction and gets regenerated as such at the end of the reaction without getting consumed.
Note: The question is incomplete. The complete question is given below :
Suppose a substance has a heat of fusion equal to 45 cal/g and a specific heat of 0.75 cal/g°C in the liquid state. If 5.0 kcal of heat are applied to a 50 g sample of the substance at a temperature of 24°C, what will its new temperate be? What state will the sample be in? (melting point of the substance = 27°C; specific heat of the solid =0.48 cal/g°C; boiling point of the substance = 700°C)
Explanation:
1.a) Heat energy required to raise the temperature of the substance to its melting point, H = mcΔT
Mass of solid sample = 50 g; specific heat of solid = 0.75 cal/g; ΔT = 27 - 24 = 3 °C
H = 50 × 0.75 × 3 = 112.5 calories
b) Heat energy required to convert the solid to liquid at its melting point at 27°C, H = m×l, where l = 45 cal/g
H = 50 × 45 = 2250 cal
c) Total energy used so far = 112.5 cal + 2250 cal = 2362.5 calories.
Amount of energy left = 5000 - 2362.5 = 2637.5 cal
The remaining energy is used to heat the liquid
H = mcΔT
Where specific heat of the liquid, c = 0.75 cal/g/°C, H = 2637.5 cal, ΔT = temperature change
2637.5 = 50 × 0.75 x ΔT
ΔT = 2637.5 / ( 50*0.75)
ΔT = 70.3 °C
Final temperature of sample = (70.3 + 27) °C = 97.3 °C
The substance will be in liquid state at a temperature of 97.3 °C
i hope that this eg gonna help u
Answer:
*2Kl+Pb(NO3)2=PbI2+2KNO3: double replacement.
*2Al+3CuSO4=Al2(SO4)3+3Cu: single replacement.
*C2H5OH+3O2=2CO2+3H2O: combustion.
Explanation:
Hello there!
In this case, according to the required, it turns out necessary for us to recall the five types of reactions, combination, decomposition, single and double replacement and combustion as shown on the attached figure.
In such a way, since the first reaction follows the pattern AB+CD-->AD+CB we infer it is double replacement; the second reaction follows the patter A+BC-->AC+B and therefore it is single replacement; and the last one follows the pattern of combustion reaction due to the presence of CO2 and H2O on the products side.
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