4. A
because PbCl2 is an ionic compound and it's solid, so it's a substance.
It cannot be mixture, because it's a pure molecule.
5. D
despite that both substances are gases, colorless they are different molecules, so they should have different either chemical and physical properties
6. C
this substance made from W atoms and others are made from molecules
It is energetically favorable for all atoms to have a complete outer
electron shell. Loosely, the atoms on the left hand side of the periodic
table only have a few extra electrons in their outer shell so it is
energetically favorable for them to lose them. The atoms on the right
hand side of the periodic table almost have enough electrons in their
outer shell and so they have a tendency to gain them.
Once electrons have left an electron shell, an atom will have a positive
charge because it has more protons (positive charges) than electrons
(negative charges). Similarly, an electron which has gained electrons to
complete its outer shell will have a negative charge because it now has
more electrons (negative charge) than protons (positive charge).
The answer is "elements" :)
Answer:
Explanation:
The actual boiling point is probably between 34C and 40C.
Answer:
3.00 mol
Explanation:
Given data:
Mass of P₄ = 211 g
Mass of oxygen = 240 g
Moles of P₂O₅ = ?
Solution:
Chemical equation:
P₄ + 5O₂ → 2P₂O₅
Number of moles of P₄:
Number of moles = mass/ molar mass
Number of moles = 211 g / 123.88 g/mol
Number of moles = 1.7 mol
Number of moles of O₂ :
Number of moles = mass/ molar mass
Number of moles = 240 g / 32g/mol
Number of moles = 7.5 mol
Now we will compare the moles of product with reactant.
O₂ : P₂O₅
5 : 2
7.5 : 2/5×7.5 = 3.00
P₄ : P₂O₅
1 : 2
1.7 : 2×1.7 = 3.4 mol
Oxygen is limiting reactant so the number of moles of P₂O₅ are 3.00 mol.
Mass of P₂O₅:
Mass = number of moles × molar mass
Mass = 3 mol ×283.9 g/mol
Mass = 852 g
