Practice 2.1                                                                             Name ________________________________________


1. Classify the following as a homogeneous, O, or a heterogeneous, E, mixture.

____ a. a pail of sand and water                                    ____ d. a banana split

____ b. air                                                       ____ e. chocolate syrup

____ c. human blood                                         ____ f. sea water

2. Compare and contrast atoms and molecules.

3. Explain the difference between a pure substance and a homogeneous mixture.

4. Classify each of the following as an element or a compound.

_______________ a. benzene, C6H6                    _______________ d. titanium,Ti

_______________. aluminum, Al                     _______________ e. acetylene, C2H2

_______________ c. aspirin, C9H8O4                  _______________ f. zinc, Zn

5. Explain why elements and compounds are pure substances.

6. Determine which of the following are pure substances and which are mixtures.

_______________ a. salt water                                               _______________ d. ammonia, NH3

_______________ b. isopropyl alcohol, C3H8O                        _______________ e. an egg yolk

_______________ c. mercury, Hg                               _______________ f. honey

7. Determine the number and kinds of atoms in the following molecules.

a.       Water, H2O ______________________________________________________________________________

b.      acetylene, C2H2 ___________________________________________________________________________

c.       isopropyl alcohol, C3H8O___________________________________________________________________

d.      aspirin, C9H8O4 ___________________________________________________________________________