Explain whether this is a chemical or physical change, and why. does it involve elements, compounds, mixtures, or pure substances?
If the process involves a chemical reaction then surely it is a chemical change where new bonds are being formed from the collision of the reactants.
Describe how many atoms are involved before and after. what do you notice about the number of atoms?
From the balanced chemical reaction, we see that we need 1 mol of N2 gas and 3 mol of H2 in order to form 2 mol of NH3.
Answer : The molecular weight of a substance is 157.3 g/mol
Explanation :
As we are given that 7 % by weight that means 7 grams of solute present in 100 grams of solution.
Mass of solute = 7 g
Mass of solution = 100 g
Mass of solvent = 100 - 7 = 93 g
Formula used :
where,
= change in freezing point
= temperature of pure water = 
= temperature of solution = 
= freezing point constant of water = 
m = molality
Now put all the given values in this formula, we get
Therefore, the molecular weight of a substance is 157.3 g/mol
Answer:
SiO2(s) + 3C(s) ------> SiC(s) + 2CO(g)
Explanation:
The formula for silicon oxide is SiO2 and carbon is C. silicon carbide is SiC
and carbon monoxide is CO.
An arrow is always used to separate the reactants (left) and products (right).
A balanced equation must contain equal number of atoms in each side of the equation.
For example in the equation above, there are 1 atom of silicon appears on each side; 2 atoms of oxygen and three atoms of carbon.
The first basic metals on the periodic table are alkali metals.
