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2 years ago

4.8g of calcium is added to 3.6g of water. The following reaction occurs

1 answer:

8 0

Q1)
the number of moles can be calculated as follows
number of moles = mass present / molar mass
number of moles is the amount of substance.
4.8 g of Ca was added therefore mass present of Ca is 4.8 g
molar mass of Ca is 40 g/mol
molar mass is the mass of 1 mol of Ca
therefore if we substitute these values in the equation
number of moles of Ca = 4.8 g / 40 g/mol = 0.12 mol
0.12 mol of Ca is present

q2)
next we are asked to calculate the number of moles of water present
again we can use the same equation to find the number of moles of water
number of moles = mass present / molar mass
3.6 g of water is present

sum of the products of the molar masses of the individual elements by the number of atoms
H - 1 g/mol and O - 16 g/mol
molar mass of water = (1 g/mol x 2 ) + 16 g/mol = 18 g/mol
molar mass of H₂O is 18 g/mol
therefore number of moles of water = 3.6 g / 18 g/mol = 0.2 mol
0.2 mol of water is present

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10 points) Given the following two half-reactions, write the overall reaction in the direction in which it is product-favored, a

IceJOKER [234]

Answer:

The over all reaction :

$2Fe^{3+}(aq)+Pb(s)\rightarrow 2Fe^{2+}(s)+Pb^{2+}(aq)$

The standard cell potential of the reaction is 0,.897 Volts.

Explanation:

Reduction at cathode :

$Fe^{3+}(aq)+e^-\rightarrow Fe^{2+}(s)$ ..[1]

$E^o_{Fe^{3+}/Fe^{2+}}=0.771 V$

Reduction potential of $Fe^{3+}$ to $Fe^{2+}=0.771 V$

Oxidation at anode:

$Pb(s)\rightarrow Pb^{2+}(aq)+2e^-$ .[2]

$E^o_{Pb^{2+}/Pb}=-0.126 V$

Reduction potential of $Pb^{3+}$ to $Pb=-0.126 V$

To calculate the $E^o_{cell}$ of the reaction, we use the equation:

$E^o_{cell}=E^o_{red,cathode}-E^o_{red,anode}$

Putting values in above equation, we get:

$E^o_{cell}=E^o_{Fe^{3+}/Fe^{2+}}-E^o_{Pb^{2+}/Pb}$

$=0.771 V-(-0.126 )=0.897 V$

The over all reaction : 2 × [1] + [2]

$2Fe^{3+}(aq)+Pb(s)\rightarrow 2Fe^{2+}(s)+Pb^{2+}(aq)$

The standard cell potential of the reaction is 0,.897 Volts.

7 0

2 years ago

Given six molecules, identify the molecules with polar bonds and the molecules that are polar.CCl4, CH3Cl, H20, CO2, O2

Nikitich [7]

Answer:

Non-polar compounds: $CCl_4$ , $O_2$ , $CO_2$

Polar compounds: $CH_3Cl$ , $H_2O$

Explanation:

For this question, we must start with the Lewis structure for each molecule and then we can do their respective analysis:

-) $CCl_4$

In this case, we have 4 equal atoms attached to the central atom. Therefore, we have the same magnitude of electronegativity. Chlorine atoms have different and opposite directions. Therefore due to the orientation the dipole moments cancel and the net dipole moment will be zero and the molecule will be non-polar.

-) $O_2$

In this case, we have a linear structure in which the magnitude of the dipole moment is the same, but the direction is the opposite. Therefore the dipole moments are canceled and the molecule will be non-polar.

-) $CO_2$

In this case, we also have a linear structure in which the magnitude of the dipole moment is the same, but the direction is the opposite. Therefore the dipole moments are canceled and the molecule will be non-polar.

-) $CH_3Cl$

For this molecule, we have a different atom. The hydrogen atom, therefore the magnitude of one of the atoms attached to the central atom is different and the magnitude of the net dipole moment will be different from zero and the molecule will be polar.

-) $H_2O$

For this molecule, due to the structure of the molecule, the dipole moments of oxygens will not have a totally opposite configuration. Therefore, the net dipole moment will be different from zero and the molecule will be polar.

See figure 1 to further explanations

I hope it helps!

5 0

2 years ago

What is the pH of a solution made by mixing 15.00 mL of 0.100 M HCl with 50.00 mL of 0.100 M KOH? Assume that the volumes of the

denis23 [38]

Answer:

The correct answer is: pH = 12.73

Explanation:

The neutralization reaction between HCl and KOH is given by the following chemical equation:

HCl + KOH ⇒ KCl + H₂O

Since HCl is a strong acid and KOH is a strong base, HCl is completely dissociated into H⁺ and Cl⁻ ions, whereas KOH is dissociated completely into K⁺ and OH⁻ ions.

For acids, the number of equivalents is given by the moles of H⁺ ions (in this case: 1 equivalent per mol of HCl). For bases, the number of equivalents is given by the moles of OH⁻ ions (in this case: 1 equivalent per mol of KOH).

The H⁺ ions from HCl will react with OH⁻ ions of KOH to give H₂O. The pH is calculated from the difference between the equivalents of H⁺ and OH⁻:

equivalents of H⁺= volume HCl x Molarity HCl

= (15.0 mL x 1 L/1000 mL) x 0.100 mol/L

= 1.5 x 10⁻³ eq H⁺

equivalents of OH⁻= volume KOH x Molarity KOH

= (50.0 mL x 1 L/1000 mL) X 0.100 mol/L

= 5 x 10⁻³ eq OH⁻

There are more OH⁻ ions than H⁺ ions. The excess of OH⁻ (that did not react with H⁺ ions) is calculated as follows:

OH⁻ ions= (5 x 10⁻³ eq OH⁻) - (1.5 x 10⁻³ eq H⁺) = 3.5 x 10⁻³ eq OH⁻= 3.5 x 10⁻³ moles OH⁻

As the volumes of the solutions are additive, the total volume of the solution is:

V= 15.0 mL + 50.0 mL = 65.0 mL= 0.065 L

So, the concentration of OH⁻ ions in the solution is given by:

[OH⁻] = moles OH⁻/V= (3.5 x 10⁻³ moles OH⁻)/0.065 L = 0.054 mol/L = 0.054 M

From [OH⁻], we can calculate pOH:

pOH = -log [OH⁻] = -log (0.054) = 1.27

Finally, we know that pH + pOH= 14; so we calculate pH:

pH= 14 - pOH = 14 - 1,27 = 12.73

8 0

3 years ago

Nickel can be plated from aqueous solution according to the following half reaction. How long would it take (in min) to plate 29

andrey2020 [161]

Answer:

It take 3.5 *10² min

Explanation:

Step 1: Data given

Mass of the nickel = 29.6 grams

4.7A

Step 2: The balanced equation

Ni2+ (aq- +2e- → Ni(s)

Step 3: Calculate time

W = (ItA)/(n*F)

⇒ W = weight of plated metal in grams = 29.6

⇒ I = current in coulombs per second. = 4.7

⇒ t = time in seconds.

⇒ A = atomic weight of the metal in grams per mole. = 58.69

⇒ n = valence of dissolved metal in solution in equivalents per mole. = 2

⇒ F = Faraday's constant in coulombs per equivalent. F = 96,485.309 coulombs/equivalent.

29.6 = (4.7 * t * 58.69)/(2*96485309)

t = 20707 seconds

t =345 minutes = 3.5 * 10² min

It take 3.5 *10² min

7 0

2 years ago

Explain how manipulation of light waves can cause reflection, refraction, diffusion, and absorption; and describe how different

Effectus [21]

Answer:is A

Explanation:

6 0

2 years ago