8. The rate constant for the reaction below is 6.2 x 10−5 mol L−1s−1. If the initial concentration of A is 0.0500 M, what is its concentration after 115 s?

The concentration after 115 seconds is 0.0496 M

Explanation:

Applying integrated rate law for a first-order reaction, we will have;

where;

is the concentration at a time t

is the initial concentration

k is the rate constant for the reaction

t is the given time

Given;

 = 0.05 M

k = 6.2 x 10⁻⁵ mol L⁻¹s⁻¹

t = 115 seconds

Substitute these values and solve for

Therefore, the concentration after 115 seconds is 0.0496 M

they are both synthetic elements

explanation:

d

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.