Answer : During chemical changes only.
Explanation : A chemical change is usually when a compound or molecule undergoes a change which is normally irreversible and it generates a new product than it was before.
So, when we consider the process of making up of substances from atoms it makes the substance as an irreversible product.
Also a new product which is formed is the substance which is not at all similar to atoms.
Answer:
Fractional distillation
Explanation:
The separation of gasoline from crude oil by heating until it reaches its boiling point is a separation technique called fractional distillation.
- It is the separation of a mixture, such as crude oil into their respective fractions.
- This is achieved due to the differences in boiling point between the constituent fractions in the mixture.
- As the boiling point of a fraction is reached, it distills out from the column.
1. CH4
2. Br2
3. 25 g/mol
Graham's law indicates that the rate of diffusion is inversely proportional to the square root of its molecular weight. So the lighter the gas, the more rapid the diffusion. With that in mind, let's look at your questions:
1. A flask contains four gases: CH4, O2, C2H5, and N2. When the stopper is removed, which gas will diffuse the fastest?The answer here will be the lightest of the 4 gasses. So let's look at the molar mass of each gas:
CH4 = 16.04 g/mol
O2 = 32.00 g/mol
C2H5 = 29.06
N2 = 28.01
And CH4 is the lightest and therefore the fastest.
2. Which gas effuses 2.39 times slower than nitrogen gas? O2 Cl2 Br2 <--- I2
Let's start with the square root of 28.01 which is 5.292447449.
Now multiply by 2.39 and square the result to get the molar mass of the
desired gas which is (5.29*2.39)^2 = 12.64^2 = 159.77Now let's look at the molar masses.
O2 = 32
Cl2 = 70.91
Br2 = 159.81
I2 = 253.81
And the match goes to Br2
3. What is the molecular mass of a gas that effuses three times faster than radon? 16 g/mol 25 g/mol <--- 50 g/mol 67 g/mol,The molar mass of radon is 222 g/mol. So let's get the square root, divide by
3, then square the result. So(sqrt(222)/3)^2 = (14.89966443/3)^2 = 4.966554809^2 = 24.66666667 g/mol.And of the available choices, 25 g/mol is the best match.
Answer:
Explanation:
silicon has highest ionization energy ionization energy increases from left to right in a period because electron are added to same shell and increase in added electron shield each other poorly from the nuclear attraction
2.-> At the equivalence point, the pH = 7.00 for strong acid- strong base titrations.
3.-> A strong acid- strong base titration is performed using a phenolphthalein indicator. Phenolphtalein is chosen because it changes color in a pH range between 8.3 – 10. It will appear pink in basic solutions and clear in acidic solutions.
