The formation of a gas in a chemical reaction, due to ions changing places, often indicates that the reaction is which type?
a) synthesis

b) double-displacement

c) decomposition

d) single-displacement

The correct answer is D.

Explanation: In a chemical reaction, when there is changing of ions taking place and is leading to the formation of a gas can be considered as a single displacement reaction.

Single-Displacement reactions are defined as the reactions in which a higher reactive metal displaces a lower reactive metal. This is in reference to the reactivity series.

Hydrogen lies below in the reactivity series and when the higher reactive metal displaces hydrogen from a chemical reaction, it leads to the formation of hydrogen gas.

Example:

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.