Answer:
mass of methanol = 519.3 g
Explanation:
Given data:
molecules of CH3OH = 9.77 × 10∧ 24
mass in gram = ?
Solution:
First of all we will calculate the number of moles:
(9.77 × 10∧ 24) × 1 mol / 6.02 × 10∧23 = 16.229 moles
Now we will calculate the mass in gram:
Formula:
number of moles = mass/ molar mass
16.229 mole = mass / 32 g/mol
mass = 16.229 mol × 32 g/ mol
mass = 519.3 g
Simple method:
molar mass of CH3OH is 32 g so according to Avogadro number,
32 g of CH3OH = 6.02 × 10∧23 molecules
9.77*10^24 molecules will be equal to
(32 g of CH3OH / 6.02 × 10∧23 molecules) × 9.77*10^24 molecules
= 5.136 × 10∧-23 g/molecules × 9.77*10^24 molecules
= 519.3 g
Answer:
= 2.659 g NaCl
Explanation:
Molarity of a substance is given by the formula;
Molarity = moles/Volume in liters
Thus;
Number of moles = Molarity × volume in liters
= 1.3 M × 0.035 L
= 0.0455 Moles
But, the molar mass of NaCl is 58.44 g/mol
The mass of NaCl is therefore;
= 0.0455 g × 58.44 g/mol
<u>= 2.659 g NaCl</u>
The answer is B. Decreasing the cylinder volume decreases the amount of space the gas has to occupy there for increasing pressure
Answer:
Option a is a solution acidic ([OH⁻] = 7.0x10⁻⁹ M).
Explanation:
To know if a solution is acidic we need to calculate the pH and it must be lower than 7. A value of pH equal to 7 is a neutral solution and a solution with a pH value higher than 7 is a basic solution.
a. For the [OH⁻] = 7.0x10⁻⁹ M we have:
Now, the pH is:
This solution is acidic (pH < 7)
b. [H₃O⁺] = 8.5x10⁻⁸ M
This is not an acidic solution. Is a neutral one (pH around to 7).
c. [OH⁻] = 2.5x10⁻⁶ M
Then, the pH is:
Hence, this is not an acidic solution. It is basic (pH > 7).
Therefore, option a is a solution acidic ([OH⁻] = 7.0x10⁻⁹ M).
I hope it helps you!