Chemistry Test 2 Prep

CO is a/an

compound

What does a subscript number in a chemical formula of a compound indicate?

subscript numbers indicate how many atoms of the represented element are chemically bonded to the other element(s)

Compound

a substance made up of atoms of two or more different atoms chemically bonded together

Molecule

a substance made up of two or more atoms chemically bonded together

The primary fuel molecule in gasoline is called octane. Octanes chemical formula is C8H18. How many carbon atoms are needed to chemically bonded with the other element to form one molecule of octane?

8

What is the best answer for volume in the following image?

36.50 *Always add extra 100th decimal value

Writing Prompts

....

The correct answer for 8.98 X 0.00012

0.0011 *Rounded to the value with the least number of sig figs

How many significant figures does each of the following number have?

0.004567 - 4 100. - 3 10,000 - 1 9.0 - 2 7.60 - 3

How many Calcium atoms are bonded to the other element, in one molecule of the compound CaCl2 ?

1

How many oxygen molecules are in the reactants for the following chemical change? 2H2 + O2 ---------> 2H2O

1

The compound H2SO4 has how many Sulfur (S) atoms chemically bonded to the other elements?

1

How many different molecules are shown as products of the chemical reaciton show below? 2 H2O2 ------> 2 H2O + O2

2 *NOTICE DIFFERENT MOLECULES

How many different elements are in a molecule of sodium hydroxide, which has the chemical formula for NaOH?

3

How is it that all compounds can be classified and molecules, but not all molecules can be classified as compounds? - 1 point for correctly explaining why all compounds are also molecules - 1 point for using a specific example of a compound that is also molecule - 1 point for explaining why not all molecules are compounds - 1 point for using an example of a molecule that is not a compound)

All compounds can be classified as molecules because a molecule is formed when two or more atoms are chemically bonded together and a compound is when two or more different atoms are chemically bonded together. A compound that is also a molecule would be CO2 because is a combination of a carbon atom and two oxygen atoms.

When performing a calculation from data in chemistry, how do you decide how many significant figures to use? - 1 point for explaining how to choose significant figures - 1 point for using a specific example (a calculation of your choice) - 1 point for including units in your example

When performing a calculation from data in chemistry you pick the value with the least number of signifificant figures and report your answer to the value with the least number of significant figures. Ex: 180.2 mL - 20.2 mL = 160. mL *20.2 has 3 significant figures so the answer has to be 3 significant figures

What evidence (observations) enable you to justify if a Physical Reaction or Chemical Reaction has occurred? - 1 point for correctly explaining evidence of physical reactions - 1 point for using a specific example of a physical reaction - 1 point for explaining evidence of chemical reaction - 1 point for a specific example of a chemical reaction (molecules/compounds as reactants to molecules/compounds as products)

You could identify a physical reaction if you notice a change in shape, size, state, and sometimes color. An example of a physical reaction would be water turning from a liquid into a solid as ice, as it only changes state of matter. You could identify chemical reactions by looking for the formation of a solid or gas, permanent color change, and temperature change. An example of a chemical change would be photosynthesis, when the reactants carbon and water become glucose and oxygen.

Why are all compounds also molecules, but not all molecules are compounds?

a molecule is simply two or more atoms of any type chemically bonded together while a compound must have atoms of different elements chemically bonded. The oxygen we need for survival is considered a molecule but not a compound because both atoms that are chemically bonded are of the same element.

Which of the following choices is not a molecule?

a. NaOH b. Kr c. HCI d. water ------>Kr

Which is the smallest particle of an element that has characteristics of the element

atoms

When _________ form chemical bonds they are called ___________ . If the atoms in the molecule of are of __________ elements the substance can be referred as a _____________.

atoms, molecules, different, compounds

Co is a/an

element

I2 is a/an

element

What place value is this electronic balance accurate to?

hundredths *ending with ths

Whole numbers that have a zero in the ones place are not considered a significant figure except when..

proceeded by a decimal point.

When following significant figure rules and performing calculations the answer will have...

the same number of significant figures as the value with the least significant figures.