First, we determine the mass of stearic acid in the solution by multiplying the given concentration by the volume.
mass of stearic acid = (5.4 x 10^-4 g/L) (0.25 mL) (1000 mL/1L)
= 0.135 g
Then, we divide this amount by the molar mass in order to obtain the number of moles of stearic acid. The molar mass of stearic acid is 284.4772 g/mol.
moles stearic acid = 0.135 g / (284.4772 g/mol)
= <em>4.75 x 10^-4 mol</em>
C. marbles placed inside hollow sphere
5.512 litres is the volume of 15.2 grams of sulphur dioxide gas at STP.
Explanation:
Data given:
mass of sulphur dioxide = 15.2 grams
conditions is at STP whech means volume = 22.4 litres
atomic mass of sulphur dioxide = 64.06 grams/mole
Number of moles is calculated as:
number of moles = 
Putting the values in the equation:
number of moles = 
= 0.23 moles
Assuming that sulphur dioxide behaves as an ideal gas, we can calculate the volume as:
When 1 mole of sulphur dioxide occupies 22.4 litres at STP
Then 0.23 moles of sulphur dioxide occupies 22.4 x 0.23
= 5.152 litres is the volume.
Positron emission = emission of a positron and a neutrino when a
proton is convert into a neutron. The total number of particles in the
nucleus doesn't change, -1 proton +1 neutron
It's a spontaneous reaction for some nucleus.
eg:
Positron = e+
Neutrino=ve
O-15 --> N-15 + e+ +ve
Electron
capture= A nucleus absorb an electron while a proton is convert in a
neutron and emit a neutrino. The total number of particles in the
nucleus doesn't change, -1 proton +1 neutron
eg:
Al-26 +e- --> Mg-26 + ve
Electron
capture and positron emission are two mechanisms to explain the decay
of some unstable isotopes. Electron capture is usually observed when the
energy difference between the initial and final state is low. Mainly
because of the larger amount of kinetic energy need for the expulsion
two particles with the positron emission mechanism.
The time it took her to drive 2 km is 11.43 seconds, because sonverting kilometers to meters, it is 1000 meters to every kilometer, and she travels 2 kilometers, which is two-thousand meters. Then to find the time you need to divide the time by the speed, and with that you get 11.4285714286, or 11.43 seconds.
