<span>Pre-1982 definition of STP: 37 g/mol
Post-1982 definition of STP: 38 g/mol
This problem is somewhat ambiguous because the definition of STP changed in 1982. Prior to 1982, the definition was 273.15 K at a pressure of 1 atmosphere (101325 Pascals). Since 1982, the definition is 273.15 K at a pressure of exactly 100000 Pascals). Because of those 2 different definitions, the volume of 1 mole of gas is either 22.414 Liters (pre 1982 definition), or 22.71098 liters (post 1982 definition). And finally, there's entirely too many text books out there that still use the 35 year obsolete definition. So let's solve this problem using both definitions and you need to pick the correct answer for the text book you're using.
First, determine how many moles of gas you have. Just simply divide the volume you have by the molar volume.
Pre-1982: 2.1 / 22.414 = 0.093691443 moles
Post-1982: 2.1 / 22.71098 = 0.092466287 moles
Now determine the molar mass. Simply divide the mass by the moles. So
Pre-1982: 3.5 g / 0.093691443 moles = 37.35666667 g/mol
Post-1982: 3.5 g / 0.092466287 moles = 37.85163333 g/mol
Finally, round to 2 significant figures. So
Pre-1982: 37 g/mol
Post-1982: 38 g/mol</span>
There is no way to know which reaction requires which catalyst. However, if you apply copper to a reaction where it does act as a catalyst, the rate of reaction will be much faster as it lowers the activation energy for successful collisions.
Answer:
Either direction
Explanation:
If you cook food it would go from cold to hot. If you were to put a drink in the fridge it would go from hot to cold. So it is either direction.
Answer:
1) Write the balanced equation:
2C2H6 + 7O2 ---> 4CO2 + 6H2O
2) Determine limiting reagent:
C2H6 ⇒ 13.8 g / 30.0694 g/mol = 0.45894 mol
O2 ⇒ 45.8 g / 31.9988 g/mol = 1.4313 mol
C2H6 ⇒ 0.45894 / 2 = 0.22947
O2 ⇒ 1.4313 / 7 = 0.20447
Oxygen is limiting.
3) Determine theoretical yield of water:
The oxygen : water molar ratio is 7 : 6
7 is to 6 as 1.4313 mol is to x
x = 1.2268286 mol of water
4) Convert moles of water to grams:
1.2268286 mol times 18.015 g/mol = 22.1 g (to three sig figs)
Solution to (b):
14.2 g / 22.1 g = 64.2%
Explanation:
