Answer:
2.04 x 10²⁴ molecules
Explanation:
Given parameters:
Mass of Be(OH)₂ = 145.5g
To calculate the number of molecules in this mass of Be(OH)₂ we follow the following steps:
>> Calculate the number of moles first using the formula below:
Number of moles = mass/molarmass
Since we have been given the mass, let us derive the molar mass of Be(OH)₂
Atomic mass of Be = 9g
O = 16g
H = 1g
Molar Mass = 9 + 2(16 + 1)
= 9 + 34
= 43g/mol
Number of moles = 145.5/43 = 3.38mol
>>> We know that a mole is the amount of substance that contains Avogadro’s number of particles. The particles can be atoms, molecules, particles etc. Therefore we use the expression below to determine the number of molecules in 3.38mol of Be(OH)₂:
Number of
molecules= number of moles x 6.02 x 10²³
Number of molecules= 3.38 x 6.02 x 10²³
= 20.37 x 10²³ molecules
= 2.04 x 10²⁴ molecules
A quantity of property that must be transferred to body to the physical system to perform work
Answer:
5.81 moles
Explanation:
To find the number of moles (n) in 3.5 x 10²⁴ molecules of methane gas, we divide the number of molecules by Avagadro's number (nA). That is,
n = number of molecules ÷ 6.02 × 10²³
According to this question, 3.5 x 10^24 molecules of methane gas was given, hence,
n = 3.5 × 10²⁴ ÷ 6.02 × 10²³
n = 3.5/6.02 × 10(24 - 23)
n = 0.5814 × 10¹
n = 5.81 moles
