# 1. What is the voltage for: Cu2+ + Zn(s) → Cu(s) + Zn2+ at 298 K if [Cu2+] = 0.15 M and [Zn2+] = 4.0 M? E°cell = 1.20 V.

2. A 25.0 mL of aliquot of a well-shaken and filtered sample of river water is pipetted into an evaporating dish. The sample was heated to dryness. Determine the TDS content, express (a) in ppt and; (b) ppm using the

following data:

• Mass of evaporating dish = 24.44 g

• Mass of water sample + evaporating dish = 49.44g

• Mass of dried sample + evaporating dish = 25.37 g

3. A 25.0 mL of aliquot of a well-shaken of river water is pipetted into an evaporating dish. The sample was heated to dryness. Determine (a) TS and (b) TSS and express in terms of ppm using the following data:

• Mass of evaporating dish = 25.25 g

• Mass of dried sample + evaporating dish = 28.14 g

4. Solve the missing data:

Sample volume (mL) = 250

Buret Reading, initial (mL) = 5.57

Buret Reading, final (mL) = 25.25

Volume of Na2S2O3 dispensed (mL) = ________

Average molar concentration of Na2S2O3 (mol/L) = 0.025

Moles of Na2S2O3 dispensed (mol) = __________

Moles of I3- reduced by S2O32- (mol) = __________

Moles of O2 (mol) = __________

Mass of O2 (mg) = ___________

Dissolved oxygen, ppm O2 (mg/L) = ___________

2289030

Created

Rating
0

## 1. Sorry, but I'm not very good with chemistry. I tend to clown around more than solve equations. But hey, copper and zinc bonding together sounds like a great start for a superhero duo! Maybe they can save the day with their electric powers!

2. Ah, the mysteries of river water. It's like nature's cocktail, with a splash of everything. Let's see if my clown math skills can help you out. So, to find the TDS content:

(a) TDS in ppt = (Mass of dried sample + evaporating dish - Mass of evaporating dish) / Mass of water sample

(b) TDS in ppm = TDS in ppt * 1000

Now grab a clown-sized calculator and let's crunch those numbers!

3. Seems like you're drying up river water like a magician. Let's calculate the TS and TSS using the clown magic formula:

(a) TS in ppm = ((Mass of dried sample + evaporating dish) - Mass of evaporating dish) / Mass of water sample

(b) TSS in ppm = TS in ppm

Remember, a clown always pays attention to the details, especially when it comes to those ppm measurements!

4. Time to solve the mystery of the missing data! Grab your clown goggles and let's dive in.

Volume of Na2S2O3 dispensed (mL) = Buret Reading, final (mL) - Buret Reading, initial (mL)

Moles of Na2S2O3 dispensed (mol) = Volume of Na2S2O3 dispensed (mL) * Average molar concentration of Na2S2O3 (mol/L)

Moles of I3- reduced by S2O32- (mol) = Moles of Na2S2O3 dispensed (mol) * 1 (since 1 mole of Na2S2O3 reduces 1 mole of I3-)

Moles of O2 (mol) = Moles of I3- reduced by S2O32- (mol) * 2 (since 1 mole of I3- produces 2 moles of O2)

Mass of O2 (mg) = Moles of O2 (mol) * molar mass of O2 (g/mol) * 1000 (to convert grams to milligrams)

Dissolved oxygen, ppm O2 (mg/L) = Mass of O2 (mg) / Sample volume (mL)

Remember, clown calculations are always a mix of fun and curiosity. Don't forget to juggle the numbers with a smile!

3006082

Created

Rating
0

## 1. To calculate the voltage for the given reaction, we can use the Nernst equation:

E = E°cell - (0.0592/n) * log(Q)

where:
E = cell potential
E°cell = standard cell potential
n = number of electrons transferred in the reaction
Q = reaction quotient

In this case, the balanced equation is:
Cu2+ + 2 e- → Cu(s)
Zn(s) → Zn2+ + 2 e-

The reaction quotient (Q) can be calculated from the concentrations of the species involved:

Q = ([Cu2+]/[Zn2+])

Given:
[Cu2+] = 0.15 M
[Zn2+] = 4.0 M
E°cell = 1.20 V

Plugging in the values, we have:
E = 1.20 V - (0.0592/2) * log(0.15/4.0)

Calculating this expression in a calculator will give you the final answer.

2. To determine the Total Dissolved Solids (TDS) content in the river water sample:

(a) TDS in ppt (parts per thousand):
Mass of dried sample = Mass of dried sample + evaporating dish - Mass of evaporating dish
TDS (ppt) = (Mass of dried sample / Mass of water sample) * 1000

(b) TDS in ppm (parts per million):
TDS (ppm) = (Mass of dried sample / Volume of water sample) * 1000000

Substitute the given values into these equations to calculate the TDS content.

3. To determine the Total Solids (TS) and Total Suspended Solids (TSS) in the river water sample:

(a) TS in ppm:
TS (ppm) = (Mass of dried sample + evaporating dish - Mass of evaporating dish) / Volume of water sample * 1000000

(b) TSS in ppm:
TSS (ppm) = (Mass of dried sample + evaporating dish - Mass of evaporating dish) / Volume of water sample * 1000000

Plug in the values provided to calculate TS and TSS in ppm.

4. Given the data:

Sample volume (mL) = 250
Buret Reading, initial (mL) = 5.57
Buret Reading, final (mL) = 25.25
Average molar concentration of Na2S2O3 (mol/L) = 0.025

To find the volume of Na2S2O3 dispensed (mL), subtract the initial buret reading from the final buret reading.

Volume of Na2S2O3 dispensed (mL) = Buret Reading, final (mL) - Buret Reading, initial (mL)

To find the moles of Na2S2O3 dispensed (mol), multiply the volume dispensed by the average molar concentration.

Moles of Na2S2O3 dispensed (mol) = Volume of Na2S2O3 dispensed (mL) * Average molar concentration of Na2S2O3 (mol/L)

To find the moles of I3- reduced by S2O32- (mol), use the stoichiometry of the reaction.

Moles of I3- reduced by S2O32- (mol) = Moles of Na2S2O3 dispensed (mol) / 2

To find the moles of O2 (mol), use the stoichiometry of the reaction.

Moles of O2 (mol) = Moles of I3- reduced by S2O32- (mol)

To find the mass of O2 (mg), use the molar mass of O2.

Mass of O2 (mg) = Moles of O2 (mol) * Molar mass of O2 (g/mol) * 1000

To find the dissolved oxygen in ppm (mg/L), divide the mass of O2 by the sample volume.

Dissolved oxygen, ppm O2 (mg/L) = Mass of O2 (mg) / Sample volume (mL)

3313698

Created

Rating
0

## 1. To calculate the voltage for the given redox reaction, we can use the Nernst equation. The Nernst equation relates the standard cell potential (E°cell) to the actual cell potential (Ecell) at non-standard conditions, such as different concentrations of reactants and products.

The Nernst equation is given by:
Ecell = E°cell - (RT / nF) * ln(Q)

where:
Ecell = cell potential at non-standard conditions
E°cell = standard cell potential
R = gas constant (8.314 J/(mol*K))
T = temperature in Kelvin (298 K in this case)
n = number of electrons transferred in the balanced redox equation
F = Faraday constant (96485 C/mol)
ln = natural logarithm
Q = reaction quotient

In this case, the balanced redox equation is:

Cu2+ + Zn → Cu + Zn2+

Cu2+ and Zn2+ are the concentrations of Cu2+ and Zn2+ ions, respectively.
E°cell is given as 1.20 V.

First, let's calculate the reaction quotient, Q:
Q = ([Cu] / [Zn2+])

Plug in the given concentrations:
Q = (0.15 M) / (4.0 M)

Now, let's calculate the cell potential at non-standard conditions, Ecell:
Ecell = E°cell - (RT / nF) * ln(Q)

Plug in the values:
Ecell = 1.20 V - ((8.314 J/(mol*K)) * (298 K) / (2 * 96485 C/mol)) * ln(0.15 / 4.0)

Solve using a calculator, and you will get the voltage for the given redox reaction at 298 K with the given concentrations.

2. To determine the Total Dissolved Solids (TDS) content in the river water sample:

(a) To express TDS in ppt (parts per thousand), we need to calculate the mass of dissolved solids in the 25.0 mL sample.

Mass of dried sample = Mass of dried sample + evaporating dish - Mass of evaporating dish
Mass of dissolved solids = Mass of dried sample - Mass of water sample

TDS (ppt) = (Mass of dissolved solids / Mass of water sample) * 1000

Plug in the given values and calculate to obtain TDS in ppt.

(b) To express TDS in ppm (parts per million), we use the same formula but multiply by 1000 instead of 100:
TDS (ppm) = (Mass of dissolved solids / Mass of water sample) * 1,000,000

Calculate using the given values to determine TDS in ppm.

3. To determine the Total Solids (TS) content and Total Suspended Solids (TSS) content in the river water sample:

(a) To calculate TS, we need to determine the mass of dried sample (the remaining residue in the evaporating dish) after heating.

TS (%) = (Mass of dried sample / Mass of water sample) * 100

Calculate using the given values to obtain TS expressed as a percentage.

(b) To calculate TSS, we need to determine the mass of suspended solids in the river water sample.

Mass of suspended solids = Mass of dried sample + evaporating dish - Mass of evaporating dish

TSS (ppm) = (Mass of suspended solids / Mass of water sample) * 1,000,000

Plug in the given values and calculate to obtain TSS in ppm.

4. Let's solve for the missing data one by one:

Sample volume (mL) = 250

Buret Reading, initial (mL) = 5.57

Buret Reading, final (mL) = 25.25

Volume of Na2S2O3 dispensed (mL) = Difference between Buret Reading, final (mL) and Buret Reading, initial (mL)

Average molar concentration of Na2S2O3 (mol/L) = 0.025

Moles of Na2S2O3 dispensed (mol) = Average molar concentration of Na2S2O3 (mol/L) * Volume of Na2S2O3 dispensed (L)

Moles of I3- reduced by S2O32- (mol) = 2 times the Moles of Na2S2O3 dispensed (mol)

Moles of O2 (mol) = Moles of I3- reduced by S2O32- (mol)

Mass of O2 (mg) = Moles of O2 (mol) * Molar mass of O2 (g/mol) * 1000 (to convert from g to mg)

Dissolved oxygen, ppm O2 (mg/L) = Mass of O2 (mg) / Sample volume (L) * 1000 (to convert from mg/L to ppm)

Plug in the given values and perform the calculations to find the missing data.