Number of atoms are calculated using a number known as "Avogadro's number."
Okay, lets see a breakdown of this. Let's say that you are given an amount of grams of a substance. For this case, lets say that that substance is Carbon (C). And, lets assume that you are given 4.01 g of Carbon, and you are tasked to find the number of atoms in that mass of Carbon. The breakdown would be as follows, with dimensional anaysis:
4.01
g Carbon
(
1
mol Carbon
12.01
g Carbon
)
(
6.022
⋅
10
23
a
t
m
s
C
a
r
b
o
n
1
mol Carbon
)
=
2.01
⋅
10
23
atms Carbon
Basically, I first wrote down the amount in grams, and I used the molar mass of Carbon (which can be found on the periodic table under Carbon) 12.01 g/mol to convert 4.01 g of Carbon to moles of Carbon. Then, I used "Avogadro's Number", or
6.022
⋅
10
23
atoms per mole
to convert the mole amount to atoms of Carbon.
The process should be very similar with other such atoms, just make sure to keep your periodic table and calculator handy.
I hope that helps!
Answer:
a) 0.1783 mol
b) 1.07*10^23 atoms
Explanation:
Step 1: Data given
Mass of gold (Au) = 35.12 grams
Molar mass of gold (Au) = 196.97 g/mol
Number of Avogadro = 6.022 *10^23 /mol
Step 2: Calculate number of moles gold
Number of moles = Mass of gold / molar mass of golf
Number of moles = 35.12 grams / 196.97 g/mol
Number of moles = 0.1783 moles
Step 3: Calculate number of atoms of gold
Number of atoms = number of moles * Number of Avogadro
Number of atoms = 0.1783 * 6.022 *10^23/ mol
Number of atoms = 1.07*10^23 atoms
Answer:
Density, 
Explanation:
Given that,
Mass of a flask is 450 g
Volume of benzene added to the flask is 145 mL or 145 cm³
The weight of the flask and benzene is found to be 754 g.
We need to find the density of the benzene.
Weight of benzene added = total weight of flask and benzene-mass of flask
m = 754 g - 450 g
m = 304 g
Density = mass/volume
So,
So, the density of the benzene is 
.
Answer: A bromine radical is more stable than chlorine radical, so it is less reactive and more choosy.
Explanation:
A chlorine atom being more electronegative in nature is able to attract a hydrogen atom more readily towards itself as compared to a bromine atom.
Since bromine is less electronegative in nature so bromine will be more selective as a hydrogen abstracting agent. As a result, bromine radical is more stable in nature than chlorine radical.
Thus, we can conclude that bromine radical is more stable than chlorine radical, so it is less reactive and more choosy.
Answer:
150 g/mol
Explanation:
Let's consider the complete neutralization of a diprotic acid H₂X with NaOH.
H₂X + 2 NaOH → Na₂X + 2 H₂O
40.0 mL of 0.200 M NaOH. were required to reach the endpoint. The reacting moles of NaOH are:
0.0400 L × 0.200 mol/L = 8.00 × 10⁻³ mol
The molar ratio of H₂X to NaOH is 1:2. The reacting moles of H₂X are 1/2 × 8.00 × 10⁻³ mol = 4.00 × 10⁻³ mol.
4.00 × 10⁻³ moles of H₂X have a mass of 0.600 g. The molar mass of H₂X is:
0.600 g/4.00 × 10⁻³ mol = 150 g/mol
