1. to calculate molar mass , you need average atomic mass of each element.
formula is simple
suppose we have Na2CO3
here it says
there are
2 atoms of Na
1 atom of C
3 atom of O
now
molar mass = (total atoms of Na × average atomic mass of Na) + ( total atom of C × average atomic mass of C )+ (total atom of O × average atomic mass of O)
i hope you can figure out it now.
in case of (NH4)2
this means you have 2 count of NH4
so total atoms of N = 2
total atoms of H = 4×2 = 8
so on you can now figure it out
2. balanced equation
here LHS and RHS shoild have same number of atoms of each element .
for example
H2 + Cl2 => 2HCl
here 2 atoms of H combined with 2 atoms of Cl , we know H and Cl combined and formed HCl now because total H atoms are 2 and Cl atoms are 2 in LHS then we should also have 2 atoms of each in right side
so thats why we have 2HCl in right side.
Try to figure out . let me know if need any help
I believe this is the best one:
B. The volume of water will increase if cooled from 3°C to 2°C.
I don't think D) because water expands from 4°C to 0°C
"When liquid water is cooled, it contracts like one would expect until a temp of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point."
Answer : The normal boiling point of ethanol will be, or
Explanation :
The Clausius- Clapeyron equation is :
where,
= vapor pressure of ethanol at = 98.5 mmHg
= vapor pressure of ethanol at normal boiling point = 1 atm = 760 mmHg
= temperature of ethanol =
= normal boiling point of ethanol = ?
= heat of vaporization = 39.3 kJ/mole = 39300 J/mole
R = universal constant = 8.314 J/K.mole
Now put all the given values in the above formula, we get:
Hence, the normal boiling point of ethanol will be, or
Answer: But-2-enoic acid has
11 Sigma Bonds and
2 Pi Bonds.
Explanation: The sigma bonds which are formed due to head to head overlap of partally filled orbitals are shown in
red color, while Pi bonds which are formed after the formation of sigma bond by overlap of orbitals perpendicular to the sigma bond are shown in
blue color.