<u>Answer:</u> The amount of sample left after 20 years is 288.522 g and after 50 years is 144.26 g
<u>Explanation:</u>
We are given a function that calculates the amount of sample remaining after 't' years, which is:
Putting values in above equation:
Hence, the amount of sample left after 20 years is 288.522 g
Putting values in above equation:
Hence, the amount of sample left after 50 years is 144.26 g
Here is an acid-base reaction. Hydrochloric acid (HCl) reacts with strontium hydroxide [ Sr(OH)2 ]
Ions H+ and OH- neutralize each other. If the amounts are not equal, one of them will be in excess.
Follow the steps as
1. Find moles of ions: mole= Molarity * Volume (in liter) ; n= M * V OR millimole = Molarity * Volume (in ml) ;
2. Write the equation
3. Find out excess ion
4. Use final volume (V acid + V base ) to calculate concentration of excess ion.
n HCI = 28 ml * 0.10 M = 0.28 mmol, releases 0.28 mmol H+ ions
n Sr(OH)2= 60 ml * 0.10 M= 0.60 mmol, releases 2* 0.60=1.20 mmol OH- ions
since Sr(OH)2⇒ Sr2+ + 2OH-
Neutralization reaction is OH- + H+ ---> H2O. The ratio is 1:1. That means 1 mmol hydroxide ions will neutralize 1 mmol hydrogen ions. Since OH- ions are greater in amount, they will be in excess
n(OH-) - n(H+)= 1.20 - 0.28 = 0.92 mmol OH- ions UNREACTED.
Total volume= V acid + V base= 28 ml + 60 ml = 98 ml
Molarity of OH- ions= mole / Vtotal = 0.92/98= 0.009 M
The answer is 0.009 M.
Answer:
Molar mass of MgCl2 is 95 g/mol
Mg = 24 g/mol and Cl = 35.5 ×2 = 71 g/mol
moles = mass given/ molar mass
= 2.7/95 = 0.028 mol
volume = 250/1000 = 0.25 dm3 (ml is the same as dm3)
molarity of MgCl2 = moles/volume
= 0.028/0.25
= 0.112 mol/dm3
Answer:
rate of recrystallization = 4.99 × 10⁻³ min⁻¹
Explanation:
For Avrami equation:
To calculate the value of k which is a dependent variable for the above equation ; we have:
The time needed for 50% transformation can be determined as follows:
![y = 1-e ^{(-kt^n)} \\ \\ e^{(-kt^n)} = 1-y\\ \\ -kt^n = In(1-y) \\ \\ t =[ \dfrac{-In(1-y)}{k}]^{^{1/n}}](https://tex.z-dn.net/?f=y%20%3D%201-e%20%5E%7B%28-kt%5En%29%7D%20%5C%5C%20%5C%5C%20e%5E%7B%28-kt%5En%29%7D%20%3D%201-y%5C%5C%20%5C%5C%20-kt%5En%20%3D%20In%281-y%29%20%5C%5C%20%5C%5C%20t%20%3D%5B%20%5Cdfrac%7B-In%281-y%29%7D%7Bk%7D%5D%5E%7B%5E%7B1%2Fn%7D%7D)
![t_{0.5} =[ \dfrac{-In(1-0.4)}{9.030 \times 10^{-7}}]^{^{1/2.5}}](https://tex.z-dn.net/?f=t_%7B0.5%7D%20%3D%5B%20%5Cdfrac%7B-In%281-0.4%29%7D%7B9.030%20%5Ctimes%2010%5E%7B-7%7D%7D%5D%5E%7B%5E%7B1%2F2.5%7D%7D)
= 200.00183 min
The rate of reaction for Avrami equation is:
rate = 0.00499 / min
rate of recrystallization = 4.99 × 10⁻³ min⁻¹
Step 1 : write a valanced equation..
NaOH + HCl 》NaCl + H2O
Step 2 : find the number of mole of HCl..
1000 ml ..contains 4.3 mole
15ml... (4.3÷1000)×15 =...
Stem 3 : use mole ratio....
HCl : NaOH
1 : 1
So mole is same as calculated above...
Step 4 :
3.5 mole of NaOH is in 1000ml
(4.3÷1000)×15 mole is in ....
Do the calculation
