C. Formation of a new substance
Answer:
In the shell...
Explanation:
In the electronic shell, or the orbit..
Bohr's Atomic Model was given by Niels Bohr. He proposed that the electrons inside an atom moved around in orbits or shells. There were different shells in the atom named as K, L, M, N... These were also called energy levels...
multiply the number of each atom with its molecular mass. (see the periodic table)
5*12 + 12*1 = 72 gram per mole.
Or more accurately: 5*12.01078 + 12*1.007947 = 72.149264 g/mole
Answer:
1.26*10²³ particles are present in 12.47 grams of NaCl
Explanation:
Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023 * 10²³ particles per mole. The Avogadro number applies to any substance.
So, first of all you must know the amount of moles that represent 12.47 grams of NaCl. For that it is necessary to know the molar mass.
You know:
- Na: 23 g/mole
- Cl: 35.45 g/mole
So the molar mass of NaCl is: 23 g/mole + 35.45 g/mole= 58.45 g/mole
Now you apply a rule of three as follows: if 58.45 grams are present in 1 mole of NaCl, 12.47 grams in how many moles will they be?
moles= 0.21
You apply a rule of three again, knowing Avogadro's number: if in 1 mole of NaCl there are 6,023 * 10²³ particles, in 0.21 moles how many particles are there?
number of particles= 1.26*10²³
<u><em>1.26*10²³ particles are present in 12.47 grams of NaCl</em></u>
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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.
