The chemical reaction

2 H2O + energy → 2 H2 + O2

is

1. a synthesis reaction.

2. an endothermic reaction.

3. an exothermic reaction.

4. an ionic reaction.

At standard pressure, during which physical change does the potential energy decrease?

How does the use of synthetic oil impact the natural resource from which they are derived?

A zero-order reaction has a constant rate of 4.40*10-4 m/s. if after 45.0 seconds the concentration has dropped to 1.50*10-2 m, what was the initial concentration? express your answer with the appropriate units.

Atoms of different elements can combine chemically to form compounds. Which of the following elements would be most likely to form a compound bound tightly together with covalent bonding? A.

The molar entropy of helium gas at 258C and 1.00 atm is 126.1 J K21 mol21. Assuming ideal behavior, calculate the entropy of the following. a. 0.100 mole of He (g) at 258C and a volume of 5.00 L b. 3.00 moles of He (g) at 258C and a volume of 3000.

Andy has two samples of liquids. Sample A has pH of 4, and sample B has a pH of 6. what can Andy conclude about these two samples? Sample A is a neutral b alkali c acidic Sample B is a neutral b alkali c acidic

How does a lone pair contribute to molecular shape? A. It is too small to affect the molecule's shape. B. It takes up space like an "invisible" atom. C. It forces the molecule into a tetrahedral shape. D. It lets the bonding pairs spread out more.

The are of a rectangle is 12 in^2. what is the area in cm^2. there are 2.54cm in an inch.

Which statements describe advantages of models? Check all that apply. Models make it possible to easily notice patterns. Models can be used to communicate and test design ideas. Models allow scientists to predict relationships.

Are energy levels and orbitals the same thing?