[minimat08]

Hello, I have had a go at a few of the questions, some I can do some I can't. If you could help at all I would be very appreciative but if not that is fine and thank you anyway .


1.   CO2 in solid form is called dry ice.  You have a block of dry ice that weighs 500g.  How many moles of CO2 molecules do you have?
g/mole = mass of carbon atom + mass of oxygen atoms
            = 12.01 + 32
            = 44.01g/mole

amount of moles = mass of CO2 / g/mole
                            = 500 / 44.01
                            = 11.361 moles of CO2


2.   Olive oil is almost pure triolein (a molecule).  The molar mass of triolein is 885 g/mol.  How many moles of olive oil molecules have you got in 500g of olive oil?






3.   How many moles of water molecules are in 1 litres of water (assume that the density of water is 1g/ml)?
1.00L x 1000mL = 1.00 x 103 mL x 1.00 g = 1.00 x 103 g
                 1 L                     1 mL

1.00 x 103 g x 1 mol = 55.6 mol x 6.02 x 1023  molecules = 3.34 x 1025 molecules
      18 g                1 mol



4.   Cyclopropane, C3H6 is an anaesthetic given by inhalation. How many grams are in a 0.250 mole sample of cyclopropane?
molar mass of C3H6 = (3 x 12.01) + (6 x 1.008) = 42.078 g/mol

mass of C3H6 = molar mass x moles
                        = 42.078 g/mol x 0.250 moles
                        = 10.519 grams



5.   Isotonic saline is often given to patients intravenously to replenish lost fluids.  Isotonic saline is a 0.9% (g/100ml) solution of salty water.  You are asked to make up 2 litres of isotonic saline.  How much salt should you weigh out?


6.   If we combine nitrous oxide (NO, laughing gas) with oxygen (O2) we produce nitrogen dioxide (NO2) according to the following reaction:

2NO + O2→ 2NO2

How many grams of NO2 will be produced when 5.00 moles of NO react?












7.   A recompression chamber 3 m x 3 m x 2 m is filled with a mixture of oxygen and nitrogen to relieve divers from the effects of the "bends”.What is the volume of the chamber in cm3?  Make sure to express your answer in scientific notation.









8.   Hydrogen and oxygen gas combine explosively to produce water.  Write a balanced chemical equation for this process.  If 10 mol of hydrogen reacted with oxygen, what volume of liquid water could be produced?












9.   You sometimes hear in a medical show on TV something like “Give the patient 200 cc’s of medicine X”.
Given that a litre is a cubic decimetre, and that a cc is short for cubic centimetre, show that a cc is also a millilitre.

1L = 1 cubic centimetre
therefore 1000ml = 1 cubic centimetre
1000ml = 1000cc therefore 1ml = 1cc



10.   A label on a soft drink bottle indicates that it contains 10% sugar w/vol.  This means the sugar concentration is 10 g/100 ml.  Given a teaspoon of sugar weighs 4 g, calculate how many teaspoons of sugar you would consume if you drank a 600 ml bottle of the soft drink.

{MOD Edit -- add descriptive title}

[Borek]

Olive oil is almost pure triolein (a molecule).  The molar mass of triolein is 885 g/mol.  How many moles of olive oil molecules have you got in 500g of olive oil?

How is it different from the first problem?

How many moles of water molecules are in 1 litres of water (assume that the density of water is 1g/ml)?
1.00L x 1000mL = 1.00 x 103 mL x 1.00 g = 1.00 x 103 g
                 1 L                     1 mL

1.00 x 103 g x 1 mol = 55.6 mol x 6.02 x 1023  molecules = 3.34 x 1025 molecules
      18 g                1 mol

Why do you calculate number of molecules, if the question asks for number of moles?

[EpicWinston]

okay, number 1 looks correct to me.
1) correct

2) Just as Borek said, it is the same as number one. Maybe if you read it a bit differently it would make more sense. The question is saying 885g of olive oil = 1 mole, so how many moles does 500g equal? (885 = 1, 500 = ?). The answer should be 0.56 (I think)

3) Borek addressed that already, you did it right, but you did an unnecessary step (calculated the number of molecules). The answer was 55.6 which you already had.

4)correct

5) ok saline is a 0.9% (g/100ml) (which is just like saying for every 100mL of water you need 0.9g of salt). The question asked you for 2 liters of saline (2000mL). do you get it?  Although this logic seems like a proportion problem you should practice using dimentional analysis. the answer is 18g.

6) okay this is just like the first problem, but it envolves an extra step- the molar ratio. The molar ratio is the ratio between two atoms/molecules in a balanced reaction. In this case the ratio is between NO and NO₂. first you will convert the 5 moles of NO into moles of NO₂ using the molar ratio, then you will convert the moles of NO₂ into grams of NO₂ usuing the molar mass. The answer should be 230g I think

7) Just convert meters into centimeters and than multiply them.

8)This one is just like #6, but except you have to write the equation this time.

9) I didn't read it sorry

10) same as #5

If you need any more help just reply and I will continue to help

[minimat08]

Thanks for that guys, big *delete me*

[nobleskill]

Well played MiniMat.... well played indeed....

 

Its a windy day today huh? Hope your studies are going well and thank you for the post. Had to double check an answer myself and found the required information here.

Nobleskill