Answer:
It would take 72.9 mL of milk of magnesia.
Explanation:
First of all we have to think how the compounds react with each other and what are the products formed. In this case, the hydrochloric acid reacts with magnesium hydroxide to generate magnesium chloride and water as a subproduct. Having said that, we have to state the balanced chemical reaction to know the associated stoichiometry:
2 HCl + Mg(OH)2 → MgCl2 + 2 H2O
According to the balanced equation we know that 2 mol of HCl reacts with 1 mol of Mg(OH)2.
Now we calculate the quantity of moles of HCl that we have present in 2.0 lts of 0.10 M solution:
0.1 M HCl = 0.1 moles HCl / 1000 ml Solution
So, in 2 liters of solution we will have 0.2 moles of HCl
This 0.2 moles of acid, as we stated before, will react with 0.1 moles of Mg(OH)2, so we need to calculate the amount of milk of magnesia that has this required quantity of moles.
With the molar mass of Mg(OH)2 we calculate the weight of the compound that represents the 0.1 moles needed to react with all the HCl present in solution:
1 mol Mg(OH)2 = 58.32 g
0.1 mol = 5.832 g
Now we need to determine what volume of the milk of magnesia solution has 5.832 g of Mg(OH)2 to react with the acid:
The concentration of milk of magnesia is 8 % (w/v). This means that we have 8 gr of Mg(OH)2 per 100 ml of solution.
8 gr Mg(OH)2 per 100 mL Solution
5.832 gr Mg(OH)2 = 72.9 mL of Milk of Magnesia
Answer:
Hint As we know that the concept of mole is mainly to calculate the entities at the microscopic level that is ions, particles, molecules, electrons or atoms etc. It is found that mole is having the symbol mol.
Complete Step by step solution:
- As we are being provided with the information that there is 15 grams of lithium. As we know that the molar mass of lithium is 6.94 g/mol.
- As we know that mole is the amount of substance that has entities as there are atoms exactly in 12 g of carbon isotope. We should note that the number of entities in one mole is important because it is called the Avogadro constant. The numeric value of this constant is 6.022×1023.
- Firstly we will write the given mass as:
156.022×1023
- Now, we can find the number of moles by the formula of moles that is given mass of the substance divided by the molar mass of the substance.
moles=given massmolar mass⟹156.022×10236.94⟹15×6.946.022×1023⟹17.28×10−23moles
- Hence, we can conclude that there are 17.28×1023 moles in 15 grams of lithium.
Note:
- If we want to calculate the number of moles of an individual entity, like say A, that is dissolved in a solution of an entity say B (A+B), then we can do so by using the concept of mole fraction. The formula of mole fraction is given as moles of a substance divided by the total number of moles.
- We should not forget to write the unit after solving the solution. Explanation:
Answer:
Explanation:
Thomas is incorrect because acceleration is a vector quantity that is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity.
Answer : the hydrogen ion concentrations for pH = 7.35 and pH = 7.45 are 4.46 x 10⁻⁸ M and 3.54 x 10⁻⁸ M respectively.
When the pH of a solution is less than 7, the hydrogen ion concentration is higher and therefore the solution is acidic.
On the other hand, when the pH of a solution is greater than 7, hydroxide ion concentration is higher and the solution acts as a base.
The normal pH range of blood is given as 7.35 - 7.45 which is greater than 7. That means blood is slight basic in nature.
Let us find hydroxide ion concentration of blood.
![pOH = - log [OH-]](https://tex.z-dn.net/?f=pOH%20%3D%20-%20log%20%5BOH-%5D)
![[OH-] = 10^{-6.65}](https://tex.z-dn.net/?f=%5BOH-%5D%20%3D%2010%5E%7B-6.65%7D)
![[OH-] = 2.24 \times 10^{-7}](https://tex.z-dn.net/?f=%5BOH-%5D%20%3D%202.24%20%5Ctimes%2010%5E%7B-7%7D)
Ionic product of water is written as,
![[H+] [OH-] = 1 \times 10^{-14}](https://tex.z-dn.net/?f=%5BH%2B%5D%20%5BOH-%5D%20%3D%201%20%5Ctimes%2010%5E%7B-14%7D)
Let us plug in the calculated value of [OH-]
![[H+] = \frac{1 \times 10^{-14}}{2.24 \times 10^-7} = 4.46 \times 10^{-8} M](https://tex.z-dn.net/?f=%5BH%2B%5D%20%3D%20%5Cfrac%7B1%20%5Ctimes%2010%5E%7B-14%7D%7D%7B2.24%20%5Ctimes%2010%5E-7%7D%20%3D%204.46%20%5Ctimes%2010%5E%7B-8%7D%20M)
The hydrogen ion concentration for pH = 7.35 is 4.46 x 10⁻⁸ M
Calculation of [H+] for pH = 7.45
pOH = 6.55
[OH-] = 2.82 x 10⁻⁷
![[H+] = \frac{1 \times 10^{-14}}{2.82 \times 10^-7} = 3.54 \times 10^{-8} M](https://tex.z-dn.net/?f=%5BH%2B%5D%20%3D%20%5Cfrac%7B1%20%5Ctimes%2010%5E%7B-14%7D%7D%7B2.82%20%5Ctimes%2010%5E-7%7D%20%3D%203.54%20%5Ctimes%2010%5E%7B-8%7D%20M)
Similarly, for pH = 7.45, we get hydrogen ion concentration of 3.54 x 10⁻⁸ M.
