Adding hot cocoa to hot water would be a chemical change
Answer:
0.940mol &
0.000301mol respectively.
Explanation:
number of moles = given mass / molar mass
given mass of Nacl = 55g Molar mass = 23 + 35.5
n=m/M = 55g/58.5g/mol = 0.940mol
note- (add the atomic weights of sodium and chlorine to get the molar mass of Nacl.) = 58.5g/mol
similarly, NaCO3 = 23 + 12 + 16*3 = 83g/mol
n=m/M = 0.025g/83g/mol = 3.01 * 10^-4 = 0.000301mol
extra: If you ever get asked to put it in number of particles just use the relation of 1mole = 6.02 * 10^23 particles.
Answer:

Explanation:
Considering,
Using ideal gas equation as:
where,
P is the pressure = 760 mmHg
V is the volume = 100.0 mL = 0.1 L
m is the mass of the gas = 0.193 g
M is the molar mass of the gas = ?
Temperature = 17 °C
The conversion of T( °C) to T(K) is shown below:
T(K) = T( °C) + 273.15
So,
T = (17 + 273.15) K = 290.15 K
R is Gas constant having value = 62.36367 L. mmHg/K. mol
Applying the values as:-
M = 45.95 g/mol
This mass corresponds to
. Hence, the gas must be
.
Affects populations,
Occurs when there is genetic variation
Selects organisms with certain traits to survive.