Ch 14 & 15 Calculating

Which is correct for molarity?

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Tags

NGSS.HS-PS1-5

Which is correct for molality?

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How do you convert a given number of grams of compound X to moles of X?

a

b

c

d

? grams X

1 mole X

given grams X

1

How do you convert a given number of moles of compound X to grams of X?

a

b

c

d

given moles X

? grams X

1 mole X

1

Tags

NGSS.HS-PS1-7

Place the choices in the correct place to find how many grams of NaOH are needed to make 250 ml of 1.5 M solution. (NaOH has a formula mass of 40 g/mole)

f

e

c

d

b

a

1

250 ml solution

1 L solution

1.5 moles NaOH

40 g NaOH

1 mole NaOH

0.25 L solution

Answer explanation

Start with the amount of solution you have IN LITERS.

Next, put in the concentration so that the liters cancel out.

Finally, put in the formula mass so that moles cancel out leaving what you need GRAMS.

Because molarity is in moles per LITER, you have to use liters, not milliliters.

Which is correct for molarity?

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• 
• 
• 

Tags

NGSS.HS-PS1-5

Which is correct for molality?

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• 
• 
• 

Tags

NGSS.HS-PS1-5

Place the choices in the correct place to find how many grams of MgCl₂ are needed to make 500 ml of 0.75 M solution. (MgCl₂ has a formula mass of 95 g/mole)

f

e

c

d

b

a

1 L solution

0.5 L solution

1

0.75 moles MgCl2

1 mole MgCl2

95 g MgCl2

500 ml solution

Answer explanation

Start with the amount of solution you have IN LITERS.

Next, put in the concentration so that the liters cancel out.

Finally, put in the formula mass so that moles cancel out leaving what you need GRAMS.

Because molarity is in moles per LITER, you have to use liters, not milliliters.

Which one is true?

• 1 g = 1000 kg

• 1 g = 100 kg

• 100 g = 1 kg

• 1000 g = 1 kg

Which one is true?

• 1 L = 1000 ml

• 1 L = 100 ml

• 100 L = 1 ml

• 1000 L = 1 ml