Bohr model of an atom illustrates a nucleus with electrons circling around it. This is a useful model for understanding atoms because this clarified that atoms are actually composed of three particles: protons, neutrons and electrons. The first two are located at the center part of an atom (nucleus), while electrons are located at the outer part. Valence electrons of an atom are also vital in the creation of different chemical compounds.
Answer:
4.92 grams of sodium phosphate (Na₃PO₄) are required to make 125 milliliters of a 0.240 M.
Explanation:
Molarity is a measure of concentration that indicates the number of moles of solute that are dissolved in a given volume.
The molarity of a solution is calculated by dividing the moles of the solute by the volume of the solution:
Molarity is expressed in units
.
In this case:
- Molarity= 0.240 M
- number of moles= ?
- volume= 125 mL= 0.125 L
Replacing in the definition of molarity:

Solving:
number of moles= 0.240 M*0.125 L
number of moles= 0.03 moles
Being the molar mass of sodium phosphate 164 g/mole, that is, the mass of one mole of the compound, you can calculate the mass of 0.03 moles using the following rule of three: if 1 mole of the compound has 164 grams, 0.03 moles contains how much mass?

mass= 4.92 grams
<u><em>4.92 grams of sodium phosphate (Na₃PO₄) are required to make 125 milliliters of a 0.240 M.</em></u>
Answer:
3.87 x 10^24
Explanation:
Simply multiply the moles by avogadros number
6.42 moles of H2O x 6.022 x 10^23 molecules/1 mole of H2O = 3.87 x 10^24 molecules of H2O
1. Pure substances cannot be separated into any other kinds of matter, while a mixture is a combination of two or more pure substances.
2. A pure substance has constant physical and chemical properties, while mixtures have varying physical and chemical properties (i.e., boiling point and melting point).
3. A pure substance is pure, while a mixture is impure.