Science help please my sister is really sick and i want to help her?

Question

1. why boiling of water is a physical change rather than a chemical change.

What are indications that you are observing a chemical change rather than a physical change?

Why is flammability considered a chemical property?

Does the law of conservation of mass apply to burning a log?

explain

How could you show that the law of conservation of mass applies to melting ice?

the following as element, compound, heterogeneous mixture, or solution (homogeneous mixture).

a. hydrogen gas

b. orange juice

c. air

d. carbon dioxide (CO2)

Is heat matter ?

5. Tell whether the following are chemical or physical changes:

a. the burning alcohol lamp _______________

b. alcohol evaporating from the alcohol lamp wick _______________

6. Tell whether the following are compounds, elements, heterogeneous or homogenous mixtures.

a. salt _____________________________

b. water _____________________________

c. salt dissolved in water _____________________________

d. sand in water _____________________________

e. copper _____________________________

f. your head _____________________________

Answer 1

Ok, i won't give the answers direct, sorry, but some clues.

1. Physical change because the water stays as H2O and doesn't change into some other compound. It is easily reversible.

Change in colour, formation of gas/ precipitate, etc

Because the thing undergoes combustion, usually producing CO2 from the carbon present in the material. The material composition itself is changed

Yes. The mass of the log, plus the oxygen that it consumes when burnt, will be equal to the ashes and carbon dioxide masses. Mass is always conserved in a closed system (in classical physics).

Weigh the ice before and after it melts.

Compound, hetero, homo (almost), compound

Heat is a form of energy TRANSFER, like work. How can it be matter in classical physics? (Although modern physics has proven mass-energy equivalence....)

C, P

C, C, Hom, Het, E, and 6f i don't know your head

Answer 2

Boiling water is a physical change because nothing is chemically changed. And when water changes from one state to another, it is always a physical change

Change in odor and color are some of the ways to distinguish a chemical change from a physical change

Flammability is a chemical property because once something has been set on fire there is no way to change the object back to its original state. For example once you burn a piece of paper, you cannot not turn it back to paper.

a. hydrogen gas is an element because hydrogen is on the periodic table of elements

b. orange juice is a solution  or homogeneous mixture because the particles are the same throughout the juice and cannot be filtered out

c. Air is a heterogeneous mixture with many different elements and are not chemically combined

d. Carbon Dioxide is a compound composed of carbon and oxygen

6.

a. salt is a compound composed of Na and Cl and is chemically combined

b. water is a compound because it is made up of H and O and is chemically combined

c. salt dissolved in water is a homogeneous solution because the mixture is the same throughout

d. sand in water is a heterogeneous mixture because the sand does not dissolve and therefore is not the same throughout

e. copper is an element (Cu)

f. your head....i suppose it would be a heterogenous mixture seeing as our head is not the same throughout

hope tht helps and hope your sis feels better =]

Answer 3

I can't see how answering these questions will help your sick sister.

Answer 4

Assuming that your sister is not being held captive by a crazed schoolboy needing his physics homework done, how on earth can this make your sister get better.

Do your own homework. That way you learn?