Answer:
Explanation:
mass of the solution m = 1.6 + 75 = 76.6 g
fall in temperature = 25 - 23.34 = 1.66°C
heat absorbed = mass x specific heat x fall in temperature
= 76.6 x 1.66 x 4.18
= 531.5 J .
= .5315 kJ .
mol weight of ammonium nitrate = 80 g
heat absorbed by 1.6 g = .5315 kJ
heat absorbed by 80 g or one mole = 26.575 kJ
enthalpy change ΔH = +26.575 kJ
b )
enthalpy of hydration = 2630 kJ / mol
lattice energy = enthalpy of hydration + enthalpy change
= 2630 + 26.575
= 2656.575 kJ .
Answer:
Explanation: So, the atomic number is the number of protons present in an atom. For example, Helium's atomic number is 2, meaning it only has 2 protons. In most cases, the number of nuetrons and protons are equal, so Helium (usually) has 2 protons and 2 nuetrons - this is the nucleus. The atomic mass, or mass per nucleon is the proton and nuetron added together, so the atomic mass of Helium is about 4. Therefore, on the periodic table, as the atomic number increases by 1, the atomic mass increases by about 2 (the atomic mass is an average so it's not exact).
Answer:
A precipitate forms; the colour changes.
Step-by-step explanation:
The formation of a precipitate a colour change are always signs that a chemical reaction has occurred.
A, B, C, and D are <em>wrong.</em> They are signs of a reaction, but you did not observe them here.
Since the temperature is constant, therefore, this problem can be solved based on Boyle's law.
Boyle's law states that: " At constant temperature, the pressure of a certain mass of gas is inversely proportional to its pressure".
This can be written as:
P1V1 = P2V2
where:
P1 is the initial pressure = 1 atm
V1 is the initial volume = 3.6 liters
P2 is the final pressure = 2.5 atm
V2 is the final volume that we need to calculate
Substitute with the givens in the above mentioned equation to get the final volume as follows:
P2V1 = P2V2
1(3.6) = 2.5V2
3.6 = 2.5V2
V2 = 3.6 / 2.5 = 1.44 liters
Answer: (a) pH = 4.774, (b) pH = 4.811 and (c) pH = 4.681
Explanation: (a) pH of the buffer solution is calculated using Handerson equation:
pKa for acetic acid is 4.76. concentration of base and acid are given as 0.95M and 0.92M. Let's plug in the values in the equation and calculate the pH of starting buffer.
pH = 4.76 + 0.014
pH = 4.774
(b) When 0.040 mol of NaOH (strong base) are added to the buffer then it reacts with 0.040 mol of acetic acid and form 0.040 mol of sodium acetate.
Original buffer volume is 1.00 L. So, the original moles of sodium acetate will be 0.95 and acetic acid will be 0.92.
moles of acetic acid after addition of NaOH = 0.92 - 0.040 = 0.88
moles of sodium acetate after addition of NaOH = 0.95 + 0.040 = 0.99
Let's again plug in the values in the Handerson equation:
pH = 4.76 + 0.051
pH = 4.811
(c) When 0.100 mol of HCl are added then it reacts with exactly 0.100 moles of sodium acetate(base) and form 0.100 moles of acetic acid(acid).
so, new moles of acetic acid = 0.92 + 0.100 = 1.02
new moles of sodium acetate = 0.95 - 0.100 = 0.85
Let's plug in the values in the equation:
pH = 4.76 - 0.079
pH = 4.681
