Answer:
a)4.40 x 10^-3 M/s
b) 8.80 x 10^-3 M/s
Explanation:
Given the reaction equation;
H2O2 (aq) + 3I- (aq) + 2H+ --------> I3- (aq) + 2H2O (l)
We can now write;
a) Rate = -Δ[I-]/3Δt
- (0.868 M - 1.000 M)/ 3 (10.0 s - 0 s)
= 4.40 x 10^-3 M/s
Similarly;
b) Rate = -Δ[H+]/2Δt
- (0.868 M - 1.000 M)/ 3 (10.0 s - 0 s)
(4.40 x 10^-3 m/s) x 2
= 8.80 x 10^-3 M/s
Electric current is the flow of electrons in a wire. In metals, the outer electrons of the atoms belong to a 'cloud' of delocalised electrons. They are no longer firmly held by a specific atom, but instead they can move freely through the lattice of positive metal ions. ... Metals are good conductors of heat.
Explanation:
The first involves keeping the surface of the concrete moist by the use ponding, spraying/sprinkling, damp sand or damp hessian.
The second prevents the loss of moisture from the concrete by covering it with polythene sheeting or leaving the formwork in place.
The third involves the use of spray or roller applied curing compounds.
<span>3400 years.
The first thing to do is determine how many half lives the sample has undergone. Assuming that the level of atmospheric carbon 14 has remained consistent over time, the sample has only 2/3rd of the level of activity, so only has 2/3rds of the carbon-14 level. So calculate the logarithm to base 2 of 2/3.
log(2/3)/log(2) = -0.17609/0.30103 = -0.58496
This indicates that 0.58496 half lives have expired which is a reasonable number since if 1 half-life had been spent, the level of activity would be half of modern activity. So just multiply the number of half-lives by the half-life. So
-0.58496 * 5730 = -3351.835129
Rounding to 2 significant figures gives an estimated age of 3400 years.</span>