Answer:
8.61 mL of the HCl solution
Explanation:
The reaction that takes place is:
- 2HCl + Mg(OH)₂ → MgCl₂ + 2H₂O
From the given mass of Mg(OH)₂, we can calculate <u>the moles of HCl that are neutralized</u>:
- 4x10² mg = 400 mg = 0.400g
- 0.400g Mg(OH)₂ ÷ 58.32g/1mol = 6.859*10⁻³ mol Mg(OH)₂
- 6.859*10⁻³ mol Mg(OH)₂ *
3.429x10⁻³ mol HCl
Finally, to calculate the volume of an HCl solution, we need both the moles and the concentration. We can <u>calculate the concentration using the pH value</u>:
= [H⁺]
- 0.0398 M = [H⁺] = [HCl] *Because HCl is a strong acid*
Thus, the volume is:
- 0.0398 M = 3.429x10⁻³mol HCl / Volume
- Volume = 8.616x10⁻³ L = 8.62 mL
200 calories.
Explanation:
The (latent) heat of fusion of a material, is either one of:
1) the heat required to melt the material without
temperature change or
2) the heat removed from the material to freeze it
without temperature change.
For water this latent heat is 80 cal/g. Multiply this by
2.5 g to get 200 cal.
Answer: 
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The balanced chemical equation for showing hydrogen peroxide decomposing into hydrogen and oxygen is:
Answer:
7800 cells
Explanation:
The number of Escherichia coli cells N after n generations is given by
N = 2ⁿ × N₀ where N₀ = initial population
Now making N₀ subject of the formula, we have
N₀ = N/2ⁿ
Since n = 8 and N = 1,996,800 cells, substituting the values of the variables into the equation, we have
N₀ = N/2ⁿ
N₀ = 1,996,800 cells/2⁸
N₀ = 1,996,800 cells/256
N₀ = 7800 cells
So, the initial population of Escherichia coli cells is 7800 cells.
<span>Alpha particle is nucleus
of a helium-4 atom, which is
made of two protons and
two neutrons.
Nuclear reaction: </span>₈₄²¹⁸Po → ₈₂²¹⁴Pb + α (alpha particle).<span>
Alpha decay is radioactive decay in
which an atomic nucleus emits
an alpha particle (helium
nucleus) and transforms into an atom with an atomic
number that is reduced by two and mass number that is reduced by four.</span>
