Answer:
The time required for the coating is 105 s
Explanation:
Zinc undergoes reduction reaction and absorbs two (2) electron ions.
The expression for the mass change at electrode 
is given as :
where;
M = molar mass
Z = ions charge at electrodes
F = Faraday's constant
I = current
A = area
t = time
also; = 
; replacing that into above equation; we have:
---- equation (1)
where;
A = area
d = thickness
= density
From the above equation (1); The time required for coating can be calculated as;
![[ \frac{20 cm^2 *0.0025 cm*7.13g/cm^3}{65.38g/mol}*2 \frac{moles\ of \ electrons}{mole \ of \ Zn} * 9.65*10^4 \frac{C}{mole \ of \ electrons } ] = (20 A) t](https://tex.z-dn.net/?f=%5B%20%5Cfrac%7B20%20cm%5E2%20%2A0.0025%20cm%2A7.13g%2Fcm%5E3%7D%7B65.38g%2Fmol%7D%2A2%20%5Cfrac%7Bmoles%5C%20of%20%5C%20electrons%7D%7Bmole%20%5C%20of%20%5C%20Zn%7D%20%2A%209.65%2A10%5E4%20%5Cfrac%7BC%7D%7Bmole%20%5C%20of%20%5C%20electrons%20%7D%20%20%5D%20%3D%20%2820%20A%29%20t)
= 105 s
Answer:
2.4 ×10^24 molecules of the herbicide.
Explanation:
We must first obtain the molar mass of the compound as follows;
C3H8NO5P= [3(12) + 8(1) + 14 +5(16) +31] = [36 + 8 + 14 + 80 + 31]= 169 gmol-1
We know that one mole of a compound contains the Avogadro's number of molecules.
Hence;
169 g of the herbicide contains 6.02×10^23 molecules
Therefore 669.1 g of the herbicide contains 669.1 × 6.02×10^23/ 169 = 2.4 ×10^24 molecules of the herbicide.
Answer:
-10778.95 J heat must be removed in order to form the ice at 15 °C.
Explanation:
Given data:
mass of steam = 25 g
Initial temperature = 118 °C
Final temperature = 15 °C
Heat released = ?
Solution:
Formula:
q = m . c . ΔT
we know that specific heat of water is 4.186 J/g.°C
ΔT = final temperature - initial temperature
ΔT = 15 °C - 118 °C
ΔT = -103 °C
now we will put the values in formula
q = m . c . ΔT
q = 25 g × 4.186 J/g.°C × -103 °C
q = -10778.95 J
so, -10778.95 J heat must be removed in order to form the ice at 15 °C.
The amount of substance present in a certain object with a given half-life in terms of h can be expressed through the equation,
A(t) = (A(o))(0.5)^(t/h)
where A(t) is the amount of substance after t years and A(o) is the original amount. In this item we are given that A(t)/A(o) is equal to 0.89. Substituting the known values,
0.89 = (0.5)(t / 5730 years)
The value of t from the equation is 963.34 years.
<em>Answer: 963 years</em>
The graph is not given in the question, so, the required graph is attached below:
Answer:
According to the graph, the relationship between the density of the sugar solution and the concentration of the sugar solution is directly proportional to each other as they both are increasing exponentially.
The graph shows that, the density of sugar solution will increase with the increase in concentration of sugar in the solution.
