Answer:
B. The temperature of the water when the food sample has finished burning completely.
Explanation:
Heat or thermal energy is a form of energy that transfers from one object to another due to a temperature difference between the objects. The units for heat are joules or calories.
Calorimetry is the measurement of heat energy released or absorbed in a chemical reaction. A calorimeter is used in calorimetry. The calorimeter operates on the Law of Conservation of Energy which states that energy is never created or destroyed but is transformed from one form to another or between objects.
In food calorimetry, the energy released when food is burned is measured by recording the rise in temperature of water in a calorimeter when a given mass of a food sample is burned completely.
Energy can be calculated using the formula: Q = mc ∆T
where Q = the energy in joules or calories, m = the mass in grams, c = specific heat and ∆T = the change in temperature (final temperature - initial temperature).
The temperature of the water when the food sample has finished burning completely is taken as the final temperature of the water. The sample is allowed to smolder for sometime before recording the final water temperature. This is because the water temperature will continue to rise after the flame has gone out.
Answer:
HfCl3
Explanation:
Step 1
Divide the percent by mass of each element by its relative atomic mass
Hf- 62.2/178.5, Cl-37.4/35.5
0.348, 1.054
Step2
Divide through by the lowest ratio
0.348/0.348, 1.054/0.348
1, 3
Therefore the empirical formula is HfCl3
Atomic theory is the scientific inquiry of the nature of matter, which is subject to change as new information is discovered. The answer is A.
Answer:
(a) The anode electrode which comprises the zinc electrode being placed in a water solution with low oxygen concentration.
(b) Cathodic reaction is:
⇒ 
Anodic reaction is:
⇒
Explanation:
In the given problem, we have an oxygen-concentration cell consisting of two zinc electrodes. One is immersed in a water solution with a low oxygen concentration and the other in a water solution with a high oxygen concentration. The zinc electrodes are connected by an external copper wire.
(a) Which electrode will corrode?
The electrode that will corrode is the anode electrode which comprises the zinc electrode being placed in a water solution with low oxygen concentration.
(b) Write half-cell reactions for the anodic reaction and the cathodic reaction.
Cathodic reaction is:
⇒ 
Anodic reaction is:
⇒
Answer:
4 moles, 160 g
Explanation:
The formula for the calculation of moles is shown below:

For
:-
Mass of
= 196 g
Molar mass of
= 98 g/mol
The formula for the calculation of moles is shown below:

Thus,


According to the given reaction:

1 mole of sulfuric acid reacts with 2 moles of NaOH
So,
2 moles of sulfuric acid reacts with 2*2 moles of NaOH
Moles of NaOH must react = 4 moles
Molar mass of NaOH = 40 g/mol
<u>Mass = Moles*molar mass =
= 160 g</u>