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Colt1911
1 month ago
5

An impure sample of zinc (zn) is treated with an excess of sulfuric acid (h 2 so 4) to form zinc sulfate (znso4) and molecular h

ydrogen (h 2). (a) write a balanced equation for the reaction. (b) if 0.0764 g of h 2 is obtained from 3.86 g of the sample, calculate the percent purity of the sample. (c) what assumptions must you make in (b)
Chemistry
1 answer:
VMariaS [2.8K]1 month ago
7 0

a) The completely balanced chemical reaction is:

 

Zn(s) + H2SO4(aq) --------> ZnSO4(aq) + H2 (g) 

<span>b) Initially, we determine the quantity of zinc that has reacted based on the produced H2.</span>

According to stoichiometry, 1 mole of Zn is required for each mole of H2 created, thus:

moles(Zn) = moles(H2) 

where moles are calculated as the ratio of mass to molar mass (MM)
mass(Zn) / MM(Zn) = mass(H2) / MM(H2) 
mass(Zn) = [mass(H2) / MM(H2)] * MM(Zn) 
mass(Zn) = [(0.0764 g)/(2 g/mol)] * 65.38 g/mol 
mass(Zn) = 2.49 g 

Consequently, we find 2.49 g of pure zinc in the sample, leading to a purity of zinc of: 

purity = (2.49 / 3.86) * 100 % = 64.50 % 
 

<span>c) In part (b), it is assumed that the impurities in the sample do not react with sulfuric acid to emit hydrogen. Thus, the hydrogen solely arises from the reaction of Zn with sulfuric acid.</span>

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Alekssandra [2904]

Answer:

The concentration of P in the pond at equilibrium is 0.034 g/m³

Explanation:

Given the total mass = 49.9 g

1 day = 24 hours

mass per hour;

Incoming mass = (49.9 g / day) * (1 day /24 hr )

            = 2.079 g/hr

Outgoing mass = 0

Mass lost due to sunlight = k C_{A} V  

Given the half-life = 3.4 hours

For a first-order reaction; k, the rate constant = ln2/t, where t is the half-time

                     ln 2= 0.693, V= volume

                     k = 0.693 / t_half = 0.693 / 3.4 = 0.2038 hr⁻¹

Substituting all parameters into the equation k C_{A} V;

Mass lost to sunlight = k C_{A} V  

C_{A} = Incoming mass per hour / kV

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5 0
9 hours ago
If 500.0 mL of 0.10 M Ca2+ is mixed with 500.0 mL of 0.10 M SO42−, what mass of calcium sulfate will precipitate? Ksp for CaSO4
Anarel [2728]

Answer:

The amount of calcium sulfate that precipitates is 6.14 grams.

Explanation:

Step 1: Provided data

We are mixing 500.0 mL of 0.10 M Ca^2+ with 500.0 mL of 0.10 M SO4^2−

The Ksp for CaSO4 is 2.40×10^−5.

Step 2: Determine moles of Ca^2+

Moles of Ca^2+ = Molarity of Ca^2+ * Volume

Moles of Ca^2+ = 0.10 * 0.500 L

Moles of Ca^2+ = 0.05 moles

Step 3: Determine moles of SO4^2-

Moles of SO4^2- = 0.10 * 0.500 L

Moles SO4^2- = 0.05 moles

Step 4: Compute total volume

Total volume = 500.0 mL + 500.0 mL = 1000 mL = 1L

Step 5: Compute Q

Q = [Ca2+] [SO42-]

[Ca2+] = 0.050 M and [SO42-]

Qsp = (0.050)(0.050) = 0.0025 >> Ksp

This indicates that precipitation will take place.

Step 6: Calculate molar solubility

Ksp = 2.40 * 10^-5 = [Ca2+][SO42-] =(x)(x)

2.40 * 10^-5 = x²

x = √(2.40 * 10^-5)

x = 0.0049 M (molar solubility)

Step 7: Determine total dissolved CaSO4

Total CaSO4 dissolved = 0.0049 M * 1 L * 136.14 g/mol = 0.667 g

Step 8: Calculate initial mass of CaSO4

Initial moles of CaSO4 = 0.050

Initial mass of CaSO4 = 0.050 * 136.14 g/mol

Initial mass of CaSO4 = 6.807 grams

Step 9: Calculate precipitate mass

6.807 - 0.667 = 6.14 grams.

The mass of calcium sulfate that will emerge as a precipitate is 6.14 grams.

5 0
1 month ago
How many kilowatt-hours of electricity are used to produce 4.50 kg of magnesium in the electrolysis of molten mgcl2 with an appl
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First, we need to identify the half-reaction for magnesium. It can be represented as:

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Next, we will determine the overall charge generated during the electrolysis using the information derived from the half-reaction. The calculation follows:

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The provided EMF is given in voltage. Since 1 V equals J/C, 5 V translates to 5 J/C.

Therefore, 35733388.2 C (5 J/C) = 178666941 J
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16 days ago
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