Answer:
Option E is the correct one
Explanation:
K₂Cr₂O₇ → Potassium dichromate
A ionic salt which its molar mass is 294.18 g/m
It is composed by 2 mol of K, 2 mol of Cr and 7 mol of O
2 mol of K = 78.2 g
2 mol of Cr = 104 g
7 mol of O = 112 g
In 294.2 g of compound we have __78.2 g K __ 104 g Cr ___ 112 g O
Let's calculate the percent
(78.2 / 294.2) .100 = 26.59% K
(104 / 294.2) .100 = 35.35% Cr
(112 / 294.2) . 100 = 38.06 % O
<span>he density of a material is defined as its mass per
unit volume. In this example, each volume of water is different and
therefore has a specific and unique mass. The mass of water is expressed
in grams (g) or kilograms (kg), and the volume is measured in liters (L), cubic centimeters (cm 3), or milliliters (mL).</span>
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.
<span>Molarity is expressed as
the number of moles of solute per volume of the solution. We calculate as follows:
2.80 g ( 1 mol / 56.11 g ) = 0.05 mol KOH
Molarity = 0.05 mol KOH / 750 mL ( 1 L / 1000 mL )
Molarity = 0.07 M
Hope this answers the question. Have a nice day.</span>
