Answer:
A molecule is a group of two or more atoms held together by chemical bonds. A compound is a substance which is formed by two or more different types of elements which are united chemically in a fixed proportion. All molecules are not compounds. All compounds are molecules.
<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>
Answer:
The total pressure in the container is 2 atm (Option B)
Explanation:
Step 1: Data given
The initial pressure of the PCl5(g) is 1.00 atm
Volume of the container = 1.00 L
Step 2: The balanced equation
PCl5(g) ⇋ PCl3(g) + Cl2(g)
Step 3: Calculate the total pressure in the container
1mol of ideal gas has a pressure of 1 atm
If 1 mol of PCl5 completely decomposes into 1 mol PCl3 and 1 mol Cl2
Then the pressure for 1 mol PCl3 and 1 mol Cl2 is for both 1 atm
The total pressure would be 2*1 atm = 2 atm
The total pressure in the container is 2 atm
