Given:
Mass of the ionic compound = 10.00 g
Mass of water = 75.0 g
Initial temperature of water T1= 23.2 C
Final temperature of water T2 = 31.8 C
Specific heat of water c = 4.18 J/gC
To determine:
Enthalpy of dissolution of the ionic compound
Heat gained by water equation:
Q = mcΔT
m = mass of water
c = specific heat
ΔT = change in temperature (T2-T1)
Q = 75.0 g * 4.18 J/gC * (31.8-23.2)C = 2696 J
Thus, the heat gained by water equals heat lost by the ionic compound (enthalpy of dissolution)
Therefore, q(ionic) = 2696 J
ΔH = q(ionic)/mass of ionic compound = 2696 J/10.00 g = 2.7 *10² J/g
Answer: A) enthalpy change = 2.7*10² J/g
Response:
of 
can be found in 39.5 grams of .
Clarification:
Atomic weights: P= 31, F= 19,
The molar mass equals 1 atomic weight of P + 5 atomic weights of
F= 31+5 × 19
= 31+95
=126 g/mole
The number of moles in 39.5 gm of
equals 
= 
=0.3134 moles
1 mole of any substance encompasses
0.3131 moles comprises 0.3134
Thus, of can be found in 39.5 grams of .
To determine the answer, you need to understand the formula for converting grams to moles, which will then lead you to the number of molecules.
The result is 2 moles of N2O5. The process is as follows:
(0.25 g N2O5) (1 mol/ 108 g)=2.31 molecules
Thus, the final answer is 2 molecules.
Answer:
B, C
Explanation:
The Lewis dot structures that are valid are for B and C.
Regarding A;
The Lewis representation of carbon is correct. Each of the four dots symbolizes the four valence electrons.
However, the nitrogen with a single dot above, to the left, and below and a -3 charge isincorrect. For it to have a -3 charge, it must possess 8 Lewis dots (two on each side).
The nitrogen showing four dots (on top, right, bottom and left) is incorrect.
In B;
An oxygen having two dots positioned above and below with one dot on both sides is correct , as the 6 dots indicate oxygen's valence electrons.
In C;
A carbon shows two dots at each position and has a charge of +4. This is correct because the charge reflects that it has gained four electrons giving it 8 valence electrons.
In D;
An oxygen shows two dots above, to the left and below, with a charge of -2. This is incorrect as not all Lewis dots are present. Two are missing.
Solution:
Washing Clothes & Dissolving Sugar
Clarification:
Consider each scenario:
1) For washing clothes, water is essential; without it, washing is ineffective.
2) Connecting brake pedals to brake pads requires solids, not liquids.
3) To deodorize a space, one would likely reach for an aerosol spray, which is a gas.
4) Sculpting involves solid tools and a solid medium.
5) Dissolving sugar necessitates a liquid to be effective!
6) While one might assert that paint is a liquid, it still might not fit the category; I would categorize this application as solid.
7) Gears employed in machinery are solid components!
