Stoichiometry Skills

Reading Scientific Notation

100

Write the following number in standard form

0.078 x 10⁶

78,000

200

What effect does a positive exponent have on a number written in scientific notation?

The number will get LARGER when multiplied by a positive exponent. The decimal will be moved towards the back/end of the number. 

300

Write the following number in standard notation 

13.02 x 10^-4

0.001302

400

Compare: write the following numbers in standard form and put them in order of increasing value. 

12.0 x 10² 

0.00012 x 10⁴

12,000,000 x 10^-5

1.2 < 120 < 1,200

500

Fill in the blank with the correct coefficient

(remember these numbers MUST be equivalent)

60,221,000,000 = ____________ x 10¹¹

60,221,000,00 =  0.60221 x 10^-11

Writing in Scientific notation

100

Write the following number in scientific notation with an exponent of -7:

0.00000420

42 x 10^-7

200

Write the following number in scientific notation with an exponent of -1:

19.097

190.97 x 10^-1

300

Write the following in scientific notation with an exponent of +4

23,400,000

2,340 x 10⁴

400

What is the purpose of writing numbers in scientific notation?

Scientific notation allows us to abbreviate large/small numbers without changing the value

500

DOUBLE: How do the coefficient and exponent work together to maintain the value of a number being written in scientific notation?

The exponent will do the opposite of the coefficient so the number maintains its value. If the coefficient gets bigger, the exponent will make it smaller, which allows the number to maintain the same value 

Operations with scientific notation

100

Simplify the following 

(5 x 10³)(4 x 10^-4)

20 x 10^-1

200

Simplify the following 

22 x 10⁴ 

______

11 x 10^-5

2 x 10⁹

300

Simplify:

(6 x 10^-1)(7 x 10^-5)

42 x 10^-6

400

COMPARE: Which of the following is greater?

(4x10²)(5x10^-2)

or 

(3x10^-6)(7x10⁵)

20 or 

(4x10²)(5x10^-2)

500

Simplify 

(4 x 10^-3)²

16 x 10^-6

Molar Mass

100

What is the molar mass of sodium chloride (NaCl)? round your answer to the nearest whole number.

1 x 22.99 = 22.99

1 x 35.45 = 35.45

22.99 + 35.45 = 

molar mass of 58 g/mol

200

Calculate the molar mass of beryllium chloride, BeCl₂?

round your answer to the nearest whole number

1 x 9.01 = 9.01

2 x 35.45 = 70.90

9.01 +70.90 =

molar mass of 80 g/mol

300

Calculate the molar mass of acetate, CH₃COOH?

round your answer to the nearest whole number

2 x 12.01 = 24.02                   (carbon)

4 x 1.01   =  4.04                   (hydrogen)

2 x 15.99  = 31.98                  (oxygen)

24.02 + 4.04 + 31.98 = 

molar mass of 60 g/mol

400

What is the molar mass of Ga₂(SO₃)₃?

2 x 69.72 = 139.44

3 x 32.06 = 96.18

9 x 15.99 = 143.91

139.44 + 96.18 + 143.91 = 

molar mass of 389 g/mol

500

DAILY DOUBLE

Calculate the percent composition of sodium in sodium chloride (NaCl)

Hint: use the masses of each atom and the total mass of the compound

Sodium mass (1 x 22.99)

Chlorine mass (1 x 35.43)

Molar mass of NaCl (58.44)

Percent composition = (22.99/58.44) x 100

= 39.3% sodium

Counting Atoms

100

How many sodium atoms are in the compound Na₂Cr₂O₇?

There are TWO sodium atoms in this compound

200

How many chlorine atoms are found in 2 NaCl?

There are TWO chlorine atoms in sodium chloride.

300

How many hydrogen atoms are in 5 molecules of ethanol, C₂H₆O?

There are THIRTY hydrogen atoms in 5 molecules of ethanol. 

(multiply the coefficient of 5 with the subscript of 6 to calculate the total number of atoms)

400

How many phosphorus atoms are in 2 Ca₃(PO₄)₂?

There are four phosphorus atoms in 2 molecules of calcium phosphate. 

(coefficient of 2 x subscript of 2)

500

What is the total number of oxygen atoms in 2 molecules of copper (II) nitrate, Cu(NO₃)₂?

There are twelve atoms of oxygen in 2 molecules of copper (II) nitrate. 

(coefficient of 2 x subscript of 2 x subscript of 3)