Answer:
0,12 μmol/L of MgF₂
Explanation:
Preparation of solutions is a common work in chemist's life.
In this porblem says that you measure 0,00598 μmol of MgF₂ in 50,0 mL of water and you must calculate concentration in μmol/L
You have 0,00598 μmol but not Liters.
To obtain liters you sholud convert mL to L, knowing 1000mL are 1 L, thus:
50,0 mL (1L/1000mL) = 0,05 L of water.
Thus, concentration in μmol/L is:
0,00598 μmol / 0,05 L = 0,12 μmol/L -The problem request answer with two significant digits-
I hope it helps!
Recall that a mole is defined as Avogadro's number of particles what the formula of caffeine basically tells us is that every molecule of caffeine you will have 8 atoms of carbon 10 atoms of hydrogen 4 atoms of nitrogen and 2 atoms of oxygen so if we have 0.3 moles of caffeine we will have 4*0.3 moles of nitrogen which is 0.12 and you got the idea
Answer:
16.1 s
Explanation:
The reaction, A → Products, follows first order kinetics.
So,
ln[A] = ln[A]o - kt
Where;
[A] = concentration at time= t
[A]o = initial concentration
k= rate constant
t = time taken
ln(0.205) = ln(0.850) - 0.0882t
ln(0.205) - ln(0.850) = - 0.0882t
-1.5847 - (-0.1625) = - 0.0882t
-1.5847 + 0.1625 = - 0.0882t
-1.4222 = - 0.0882t
t = -1.4222/- 0.0882
t = 16.1 s
Since HCl is a strong acid, it readily dissociates, so we can assume that there are 1.0x10^-3 M of H+ ions. We can use the formula:
pH=-log[H+]
pH=-log(1.0x10^-3)
pH=3
We can find the pOH by subtracting 14-pH:
14-3=11
pOH=11
The [OH-] can be found by using the formula:
pOH=-log[OH-]
11=-log[OH-]
10^-11=[OH-]
[OH-]=1.0x10^-10
