Differentiate between physical and chemical change

adell [148]

4) would be your correct answer

8 0

3 years ago

For the following systems at equilibrium C: CaCO3(s) ⇌ CaO(s)+CO2(g) ΔH=+178 kJ/mol D: PCl3(g)+Cl2(g) ⇌ PCl5(g) ΔH=−88 kJ/mol cl

Rama09 [41]

Explanation:

C: $CaCO_3(s)\rightleftharpoons CaO(s)+CO_2(g)$ ΔH=+178 kJ/mol

For an endothermic reaction, heat is getting absorbed during a chemical reaction and is written on the reactant side.

$A+\text{heat}\rightleftharpoons B$

Any change in the equilibrium is studied on the basis of Le-Chatelier's principle. This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.

Treat heat as a reactant and on increasing a reactant at equilibrium, shifts the reaction in the forward direction.

Increase temperature → increase in heat → forward direction

Decrease temperature → decease in heat → backward direction

System C - Increase temperature : Reaction will move forward

System C - Decrease temperature : Reaction will move backward

D: $PCl_3(g)+Cl_2(g)\rightleftharpoons PCl_5(g)$ ΔH=−88 kJ/mol

The total enthalpy of the reaction comes out to be negative .

The temperature of the surrounding will increase.

For an exothermic reaction, heat is released during a chemical reaction and is written on the product side.

$A\rightleftharpoons B+\text{ heat}$

Any change in the equilibrium is studied on the basis of Le-Chatelier's principle. This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.

Treat heat as a product and on increasing a product at equilibrium, shifts the reaction in the backward direction.

Increase temperature → increase in heat → backward direction

Decrease temperature → decease in heat → forward direction

System D - Increase temperature : Reaction will move backward

System D - Decrease temperature : Reaction will move forward

7 0

3 years ago

15 mL of acid 2 M was added to 20 mL of base 2 M into a calorimeter at room temperature (24 oC). The reaction mixture reached a

erik [133]

Answer:

here:

Explanation:

The changes in temperature caused by a reaction, combined with the values of the specific heat and the mass of the reacting system, makes it possible to determine the heat of reaction.

Heat energy can be measured by observing how the temperature of a known mass of water (or other substance) changes when heat is added or removed. This is basically how most heats of reaction are determined. The reaction is carried out in some insulated container, where the heat absorbed or evolved by the reaction causes the temperature of the contents to change. This temperature change is measured and the amount of heat that caused the change is calculated by multiplying the temperature change by the heat capacity of the system.

The apparatus used to measure the temperature change for a reacting system is called a calorimeter (that is, a calorie meter). The science of using such a device and the data obtained with it is called calorimetry. The design of a calorimeter is not standard and different calorimeters are used for the amount of precision required. One very simple design used in many general chemistry labs is the styrofoam "coffee cup" calorimeter, which usually consists of two nested styrofoam cups.

When a reaction occurs at constant pressure inside a Styrofoam coffee-cup calorimeter, the enthalpy change involves heat, and little heat is lost to the lab (or gained from it). If the reaction evolves heat, for example, very nearly all of it stays inside the calorimeter, the amount of heat absorbed or evolved by the reaction is calculated.

8 0

3 years ago

How many moles is 22.4 liters of oxygen gas at standard temperature and pressure represent

makkiz [27]

Answer:

So 1 mole

Explanation:

PV = nRT

P = Pressure atm

V = Volume L

n = Moles

R = 0.08206 L·atm·mol−1·K−1.