Answer
2.0 x 10²³ molecules.
Explanation
Given:
The number of moles of theobromide measured out = 0.333 moles.
MM of theobromide = 180.8 g/mol
What to find:
The number of molecules of theobromide the student measured.
To go from moles to molecules, multiply the number of moles by Avogadro's number.
The Avogadro's number = 6.02 x 10²³
1 mole of theobromide contains 6.02 x 10²³ molecules.
So, 0.333 moles of theobromide measured out will have (0.333 x 6.02 x 10²³) = 2.0 x 10²³ molecules.
Answer:
<u>132.15</u>
Explanation:
Molar mass N = 14.00
Molar mass H = 1.01
Molar mass H4 = 1.01 x 4 = 4.04
Molar mass NH4 = 14.00 + 4.04 = 18.04
Molar mass (NH4)2 = 18.04 x 2 = 36.08
Molar mass S = 32.07
Molar mass O = 16.00
Molar mass O4 = 16.00 x 4 = 64.00
Molar mass SO4 = 32.07 + 64.00 = 96.07
Molar mass (NH4)2SO4 = 36.08 + 96.07 = <u>132.14</u>
Answer:
The amount of drug left in his body at 7:00 pm is 315.7 mg.
Explanation:
First, we need to find the amount of drug in the body at 90 min by using the exponential decay equation:

Where:
λ: is the decay constant = 
: is the half-life of the drug = 3.5 h
N(t): is the quantity of the drug at time t
N₀: is the initial quantity
After 90 min and before he takes the other 200 mg pill, we have:

Now, at 7:00 pm we have:

Therefore, the amount of drug left in his body at 7:00 pm is 315.7 mg (from an initial amount of 400 mg).
I hope it helps you!
Answer:

Explanation:
The ideal gas law equation is an equation that relates some of the quantities that describe a gas: pressure, volume and temperature.
The equation is:

where
p is the pressure of the gas
V is the volume of the gas
n is the number of moles of the gas
R is the gas constant
T is the absolute temperature of the gas (must be expressed in Kelvin)
Here we want to solve the equation isolating p, the pressure of the gas.
We can do that simply by dividing both terms by the volume, V. We find:

So, we see that:
- The pressure is directly proportional to the temperature of the gas
- The pressure is inversely proportional to the volume of the gas
Answer:
= 25.05°C
Explanation:
Given:
the value of ΔHcomb (heat of combustion) for dimethylphthalate (C10H10O4) is = 4685 kJ/mol.
mass = 0.905g of dimethylphthalate
molar mass = 194.18g dimethylphthalate
number of moles of dimethylphthalate = ???
= 21.5°C
= 6.15 kJ/°C
= ???
since we have our molar mass and mass of dimethylphthalate ;we can determine the number of moles as;
0.905g of dimethylphthalate × 
number of moles of dimethylphthalate = 0.000466 moles
Heat released = moles of dimethylphthalate × heat of combustion
= 0.000466 moles × 4685 kJ
= 21.84 kJ
∴ Heat absorbed by the calorimeter =

21.84 kJ =6.15 kJ/°C 
21.84 KJ = 
21.84 KJ =
- 132.225 kJ
21.84 KJ + 132.225 kJ = 
154.065 kJ = 
= 
=25.05°C