2 questions I'm Stuck on in chemistry class,help!?

Question

1) Classify each of the following as a homogeneous mixture or a heterogeneous mixture.

a) Brass ( an alloy of zine and copper )

b) a salad

c) blood

d) Power drink mix dissolved in water

2) Phosphorus combines with hydrogen to form phosphine. in this reaction, 123.9g of phosphorus combines with excess hydrogen to produce 129.9g of phosphine. after the reaction,310g of hydrogen remains unreacted.

A)what mass of hydrogen is used in this reaction?

B) what is the initial mass of hydrogen before the reaction?

Answer 1

For the mixtures, a heterogenious one is where you can identify individual components or where the composition is not the same everywhere in the sample.

A salad would be heterogeneous as you can easily see lettuce, cucumber, carrots etc. Blood would be heterogenious as you could see the different cells with a microscope. The powder drink would be a homogenious mixture (assuming everything dissolves). Brass is an alloy, and if properly mixed, should be homogeneous.

For the reaction, using the numbers you gave:

Hydrogen used in the reaction:

129.9 - 123.9 = 6.0g of hydrogen

Original mass of hydrogen is:

310 + 6 = 316

Note there is a problem here somewhere as 123.9 of phosphorous is 4.00 moles and, if the reaction was complete, should have reacted with 6 moles of hydrogen, or about 12.12 g