Help me out anybody plz

2Al + 6HCl → 2AlCl3 + 3H2 If 3.0 grams of H2 were produced, how many grams of Al reacted? (Molar mass of Al = 27 g/mol, molar ma

Monica [59]

Hope it cleared your doubt.

8 0

3 years ago

Methods: Part A: Preparation of Buffers Make two buffers starting with solid material, which is the most common way to make buff

Alecsey [184]

Answer:

0,542 g of Na₂HPO₄ and 0,741 g of NaH₂PO₄.

0,856 g of Tris-HCl and 0,553 g of Tris-base

Explanation:

It is possible to use Henderson–Hasselbalch equation to estimate pH in a buffer solution:

pH = pka + log₁₀ $\frac{A^{-} }{HA}$

Where A⁻ is conjugate base and HA is conjugate acid

The equilibrium of phosphate buffer is:

H₂PO₄⁻ ⇄ HPO4²⁻ + H⁺ Kₐ₂ = 6,20x10⁻⁸; pka=7,21

Thus, Henderson–Hasselbalch equation for phosphate buffer is:

pH = 7,21 + log₁₀ $\frac{HPO4^{2-} }{H2PO4^{-} }$

If desire pH is 7,0 you will obtain:

0,617 = $\frac{HPO4^{2-} }{H2PO4^{-} }$ (1)

Then, if desire concentration of buffers is 0,10 M:

0,10 M = [HPO₄²⁻] + [H₂PO₄⁻] (2)

Replacing (1) in (2) you will obtain:

[H₂PO₄⁻] = 0,0618 M

And with this value:

[HPO₄²⁻] = 0,0382 M

As desire volume is 100mL -0,1L- the weight of both Na₂HPO₄ and NaH₂PO₄ is:

Na₂HPO₄ = 0,1 L× $\frac{0,0382mol}{1L}$ × $\frac{141,96g}{1mol}$ = 0,542 g of Na₂HPO₄

NaH₂PO₄ = 0,1 L× $\frac{0,0618mol}{1L}$ × $\frac{119,96g}{1mol}$ = 0,741 g of NaH₂PO₄

For tris buffer the equilibrium is:

Tris-base + H⁺ ⇄ Tris-H⁺ pka = 8,075

Henderson–Hasselbalch equation for tris buffer is:

pH = 8,075 + log₁₀ $\frac{Tris-base }{Tris-H^{+} }$

If desire pH is 8,0 you will obtain:

0,841 = $\frac{Tris-base }{TrisH^{+} }$ (3)

Then, if desire concentration of buffers is 0,10 M:

0,10 M = [Tris-base] + [Tris-H⁺] (4)

Replacing (3) in (4) you will obtain:

[Tris-HCl] = 0,0543 M

[Tris-base] = 0,0457 M

As desire volume is 100mL -0,1L- the weight of both Tris-base and Tris-HCl is:

Tris-base = 0,1 L× $\frac{0,0457mol}{1L}$ × $\frac{121,1g}{1mol}$ = 0,553 g of Tris-base

Tris-HCl = 0,1 L× $\frac{0,0543mol}{1L}$ × $\frac{157,6g}{1mol}$ = 0,856 g of Tris-HCl

I hope it helps!

8 0

3 years ago

The first strings of holiday lights were manufactured as series circuits. Which explains why this method is no longer used? A. I

user100 [1]

B because once the circuit is burned the lights will all go of

3 0

3 years ago

The small part of the nucleus where ribosomal subunit formation takes place

vaieri [72.5K]

The small part of the nucleus where ribosomal subunit formation takes place is called the nucleolus. This structure is found in eukaryotic cells and takes up about 25 percent of the volume of the nucleus. This structure is said to be the brain of the nucleus. It is made up of ribobucleic acids or the RNA and proteins. Its primary function is to transcript the ribosomal RNA (rRNA) and to combine these with the proteins resulting to the formation of an incomplete ribosome. Since it is closely related to a chromosomal matter of a cell and important in the production of ribosome, this structure is correlated to be one of the cause of a number of diseases.

3 0

4 years ago

If the density of an object is 60 g/cm 3 and its mass 20 grams what is its coulume in cm 3

Licemer1 [7]

3 cubic centimeters, Volume= density/ mass

7 0

4 years ago