The law of conservation of mass states that in a chemical reaction, the total mass of reactants is equal to the total mass of products. ... Because atoms are only rearranged in a chemical reaction, there must be the same number of sodium atoms and chlorine atoms in both the reactants and products.
In a flashlight, the electrical energy becomes light energy and thermal energy in the bulb.
Answer:
ΔE negative,ΔE positive,ΔE positive
Explanation:
Internal energy change of a system is positive when the system acquires energy from outside and internal energy change is negative when energy is being liberated from the system.
a Sweat evaporates from skin,cooling the skin ΔE is negative as heat energy is liberated through evaporation of sweat.
b A balloon expand against an external pressure ΔE positive because external energy is required to expand the balloon.
c An aqueous chemical reaction mixture is warmed with an external flame ΔE is positive because heat energy is provided by the external flame to warm the aqueous chemical reaction.
