Select the equations that are correctly balanced.

H2O + 2O2 → H2O2

Fe2O3 + 3H2 → 2Fe + 3H2O

Al + 3Br2 → AlBr3

CaCO3 → CaO + CO2

Explain how mass and energy can be conserved even during a chemical change.

An acetic acid buffer solution is required to have a pH of 5.27. You have a solution that contains 0.01 mol of acetic acid. What molarity of sodium acetate will you need to add to the solution

How much heat is absorbed by a 37g iron skillet when its temperature rises from 8oC to 24oC?

Cellulose, the main substance that makes up the

Which best describes a mixture? It has a single composition, and it has a set of characteristics that does not change. It can have different compositions, but it has a set of characteristics that does not change.

How many of the following elements have 2 unpaired electrons in the ground state? C Te Hf Si A) 1. B) 2. C) 3. D) 4.

Which has a higher frequency, a neutron or electron? Why?

1) Identify the intensive properties of a sample of matter: A. mass B. hardness C. color D. volume E. reflectivity

Suppose you have a buffer containing 0.400 M hydrazine and 0.300 M hydrazinium chloride at equilibrium. Then you add 25.2 g of NaOH to 2.0 L of the buffer. What change in pH is caused by the addition of the base? A) 0.99 B) 0.40 C) 8.71 D) - 0.36

The heart is an example of which level of organization within an organism? O cell organ tissue organ system O O