Question

Which of the following is a chemical change?
A.) boiling of water
B.) melting a cube of ice
C.) dissolving 10 grams of salt in water
D.) splitting water into hydrogen and oxygen

Answer 1

@douglaswinslowcooper

Answer 2

A physical change leaves the molecules with the same chemical formula.
A chemical change gives you some new chemical formulas.

Answer 3

D? @douglaswinslowcooper

Answer 4

Yes!

Answer 5

What is the mass of water that results from combining 2.0 g of hydrogen with 16.0 g of oxygen? A.) 14.0 g B.) 16.0 g C.) 18.0 g D.) 20.0 g @douglaswinslowcooper

Answer 6

Tricky. Rule out 20g, as you cannot get more mass than you started with.

Equation is 2 H2 + 1 O2 = 2 H2O Check: 4 H + 2 O on both sides.

That means that 2 moles of H2 combine with 1 mole of O2.

Figure out how many moles of each you have (2g H2 and 16 g O2) and how many moles of H2O you will get and whether some H2 or O2 will be left over
be lost to the air.

Or, hope to be lucky and guess that 2 + 16 = 18.

Answer 7

I am just going with 18! Thanks. @douglaswinslowcooper