The human population of the United States passed through the demographic transition between 1790 and 1910. How has the population changed after 1910?
Demographic Transition
40
-Birth Rate
Death Rate
Population
Growth
Birth/Death
Rates per 1000
10
Stable or
Slow Increase
Very Rapid
Increase
Slowing
Increase
Decrease, and Stable or
Then Stable Slow Docline
Stage 4 Stage 5
0
Stage 1
Stage 2
Stage 3
Oь
Ос
Od
The population has been increasing in a pattern explained by logistic growth.
The population has been decreasing at a steady rate.
The population has been fluctuating at or near carrying capacity
The population has been increasing exponentially.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.