The following does NOT indicate that a chemical change
may have taken place is fracture formation. A chemical change happens when the
substance changes its physical state and composition resulting from a chemical
reaction. This chemical reaction may either give off or absorb energy. A change
in color is a chemical change. For example, litmus paper turns to red when
placed in an acid solution. Production of gas is a chemical change. For
example, adding hydrochloric acid to the tiles of the bathroom gives a hissing
sound with gases given off. Formation of a precipitate is also a chemical
change. Change in shape is not a chemical change.
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Answer:
0.249087
Explanation:
1.5 x 10^23 atoms x 1 mole / 6. 022 x 10^23 atoms
= 0.249087
Answer:
0.250 mol
Explanation:
The reaction between Mg and O2 is given by;
2Mg + O2 --> 2MgO
From the equation above; 2 moles of Mg reacts to form 2 moles of MgO.
0.250 mol of Mg would produce x mol of MgO.
2 = 2
0.250 = x
x = 0.250 * 2/2 = 0.250 mol
