Answer:
C. Its oxidation number increases.
Explanation:
- <em><u>Oxidation is defined as the loss of electrons by an atom while reduction is the gain of electrons by an atom</u></em>.
- Atoms of elements have an oxidation number of Zero in their elemental state.
- When an atom looses electrons it undergoes oxidation and its oxidation number increases.
- For example, <em><u>an atom of sodium (Na) at its elemental state has an oxidation number of 0. When the sodium atom looses an electrons it becomes a cation, Na+, with an oxidation number of +1 , the loss of electron shows an increase in oxidation number from 0 to +1.</u></em>
<span>12.4 g
First, calculate the molar masses by looking up the atomic weights of all involved elements.
Atomic weight manganese = 54.938044
Atomic weight oxygen = 15.999
Atomic weight aluminium = 26.981539
Molar mass MnO2 = 54.938044 + 2 * 15.999 = 86.936044 g/mol
Now determine the number of moles of MnO2 we have
30.0 g / 86.936044 g/mol = 0.345081265 mol
Looking at the balanced equation
3MnO2+4Al→3Mn+2Al2O3
it's obvious that for every 3 moles of MnO2, it takes 4 moles of Al. So
0.345081265 mol / 3 * 4 = 0.460108353 mol
So we need 0.460108353 moles of Al to perform the reaction. Now multiply by the atomic weight of aluminum.
0.460108353 mol * 26.981539 g/mol = 12.41443146 g
Finally, round to 3 significant figures, giving 12.4 g</span>
Answer:
820.864 g
Explanation:
1) The atomic mass of sulfur (found from the periodic table) is 32.065 amu. Use this mass to find the molar mass of Sulfur. Sulfur is S8 so the molar mass of sulfur is:
8 × 32.065 = 256.52 g/mol
2) To find the mass use the formula:
m = n × M where <em>m</em><em> </em>is the mass, <em>n</em><em> </em>is the number of moles, and <em>M</em><em> </em>is the molar mass.
3)
Answer:
Carbon dioxide is a pure substance that is a compound
Explanation:
First consider the properties of a pure substance:
•made of only one type of atom or molecule
•has a well-defined melting point, boiling point, colour, odour, density and solubility.
Hydrogen bonds are present in the following molecules: HF AND NH3
Dipole dipole inter molecular forces occurs the molecules of H2S AND H2.
Hydrogen bonding is an electrostatic attraction between two polar groups that occur when hydrogen atom covalently bound with highly electronegative atoms.