Answer:
(B) II, IV.
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Answer:
The heat absorbed by the water is 228,948.48 J
Explanation:
Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.
In this way, between heat and temperature there is a direct proportional relationship (Two magnitudes are directly proportional when there is a constant so that when one of the magnitudes increases, the other also decreases; and the same happens when either of the two decreases .). The constant of proportionality depends on the substance that constitutes the body and its mass, and is the product of the specific heat and the mass of the body. So, the equation that allows to calculate heat exchanges is:
Q = c * m * ΔT
where Q is the heat exchanged by a body of mass m, constituted by a substance of specific heat c and where ΔT is the variation in temperature.
In this case:
- c= 4.184
- m=855 g
- ΔT= Tfinal - Tinitial= 85 °C - 21°C= 64 °C
Replacing:
Q= 4.184 *855 g* 64 C
Solving:
Q= 228,948.48 J
<u><em>The heat absorbed by the water is 228,948.48 J</em></u>
To get the empirical formula, we need to know the ratio of the moles of both lead and sulfur.
First, lets get the mass of each:
mass of lead = mass of evaporating dish and lead - mass of empty dish
= <span>26.927 - 25.000 = 1.927 gm of lead (Pb)
mass of sulfur = mass of dish and lead sulfide - mass of dish and lead
= </span><span>27.485 - 26.927 = 0.558 gm of sulfur (S)
The next step is to get the number of moles in 1.927 gm of Pb and in 0.558 gm of S:
From the periodic table:
molar mass of lead = </span>207.2 gm<span>
molar mass of sulfur = 32 gm
number of moles = mass / molar mass
number of moles of Pb = 1.927 / 207.2 = </span>0.0093 moles<span>
number of moles of S = 0.558 / 32 = </span><span>0.0174 moles
The third step is to get the ratio between the moles by dividing the number of moles of each by the smaller of the two:
1 mole of Pb (</span>0.0093 / 0.0093) reacts with 0.0174 / 0.0093 = 1.99 (approximately 2 moles) of sulfur.
Final step is to write the empirical formula based on the ratio:
Lead sulfide compound is written as : PbS2
<span>rms = (3RT/M)^1/2
Therefore, the rms of CO is:
rms(CO) = [(3)(8.3145 J/mol*K)(320 K)/(0.028 kg/mol)]^1/2
rms = [2.65x10^5 m^2/s^2]^1/2
rms = 533.9181 m/s</span>
