Answer:
This means that the isotope of silicon with a mass number of 28 is by far the most common of these three isotopes.
Explanation:
The abundance of Si-28 is 92.23%. Si-29 is 4.68% and Si-30 is 3.09%.
Because most Si atoms have a mass of 28 amu, the average mass of all silicon atoms is very close to 28.
Here is a video which summarizes how to calculate average atomic mass from data about mass and relative abundance.
Answer:
The molar concentration of HCl in the aqueous solution is 0.0131 mol/dm3
Explanation:
To get the molar concentration of a solution we will use the formula:
<em>Molar concentration = mass of HCl/ molar mass of HCl</em>
<em></em>
Mass of HCl in the aqueous solution will be 40% of the total mass of the solution.
We can extract the mass of the solution from its density which is 1.2g/mL
We will further perform our analysis by considering only 1 ml of this aqueous solution.
The mass of the substance present in this solution is 1.2g.
<em>The mass of HCl Present is 40% of 1.2 = 0.48 g.</em>
The molar mass of HCl can be obtained from standard tables or by adding the masses of Hydrogen (1 g) and Chlorine (35.46 g) = 36.46g/mol
Therefore, the molar concentration of HCl in the aqueous solution is 0.48/36.46 = 0.0131 mol/dm3
They added tubes thats the answer
This question asks to compare the energy emitted by a piece of iron at T = 603K with the energy emitted by the same piece at T = 298K.
Then you need to use the Stefan–Boltzmann Law
That law states that energy emitted (E) is proportional to fourth power of the to the absolute temperature (T), this is E α T^4 (the sign α is used to express proportionallity.
Then E (603) / E (298) = [603K / 298K]^4 = 16,8
Which meand that the Energy emitted at 603 K is 16,8 times the energy emitted at 298K.