Suppose an EPA chemist tests a 250.mL sample of groundwater known to be contaminated with nickel(II) chloride, which would react with silver nitrate solution like this: NiCl2(aq) + 2AgNO3(aq) → 2AgCl(s) + NiNO32(aq) The chemist adds 15.0mM silver nitrate solution to the sample until silver chloride stops forming. He then washes, dries, and weighs the precipitate. He finds he has collected 5.8mg of silver chloride. Calculate the concentration of nickel(II) chloride contaminant in the original groundwater sample. Round your answer to 2 significant digits.

Answers

Answer 1

Answer:

0.0010 w/v %

Explanation:

Based on the reaction:

NiCl₂(aq) + 2AgNO₃(aq) → 2AgCl(s) + Ni(NO₃)₂(aq)

Finding the moles of AgCl produced we can find the moles of NiCl in the reaction medium and its mass:

Moles AgCl -Molar mass: 143.32g/mol-:

5.8mg = 5.8x10⁻³g * (1mol / 143.32g) = 4.047x10⁻⁵ moles AgCl

Moles NiCl₂:

4.047x10⁻⁵ moles AgCl * (1mol NiCl₂ / 2mol AgCl) = 2.023x10⁻⁵ moles NiCl₂

Mass NiCl₂ -Molar mass: 129.60g/mol-:

2.023x10⁻⁵ moles NiCl₂ * (129.60g / mol) = 2.62x10⁻³g of NiCl₂ are produced.

And the concentration in w/v% is:

2.62x10⁻³g NiCl₂ / 250mL * 100 =

0.0010 w/v %

Related Questions

Fill in the blanks. 3NH3

Answers

Answer:

3, 9, 3

Explanation:

The coefficient of 3 tells us that there are three molecules (the chemical unit of NH3). Each molecule of ammonia (NH3) is made up of 1 atom of nitrogen bonded to 3 atoms of hydrogen.

Since there are three molecules, we have three times the amount of atoms there are in one molecule.

3 x 1 = 3 nitrogen

3 x 3 = 9 hydrogen

A severe storm would be most likely to damage a coastal area by causing
A.
volcanoes.
B.
pollution.
C.
erosion.
D.
earthquakes.

Answers

D earthquakes


my teacher told me

A severe storm would be most likely to damage a coastal area by causing pollution. Therefore, the correct option is option B.

What is coastal area?

The region where land joins the ocean, or even as a line defining the border between the land as well as the shoreline, is known as the coast, sometimes referred as the coastline and seashore. The terrain of the area's surroundings has an impact on shorelines, as do water-induced erosion processes like wave action.

The length of the shoreline on Earth is about 620,000 kilometers. Natural ecosystems' coasts are significant zones and frequently the site of a diverse range of biodiversity. They are home to significant ecosystems on land, such as freshwater and estuarine wetlands, that are crucial for the survival of bird populations or other land animals. A severe storm would be most likely to damage a coastal area by causing pollution.

Therefore, the correct option is option B.

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Calculate the pH of each of the following aqueous solutions. (Enter your answers to two decimal places.) (a) 10.0 mL deionized water WebAssign will check your answer for the correct number of significant figures. 2.72 Incorrect: Your answer is incorrect. (b) 10.0 mL deionized water plus 5.0 mL of 0.10 M NaOH WebAssign will check your answer for the correct number of significant figures. (c) 10.0 mL deionized water plus 10.0 mL of 0.10 M NaOH WebAssign will check your answer for the correct number of significant figures. (d) 10.0 mL deionized water plus 15.0 mL of 0.10 M NaOH WebAssign will check your answer for the correct number of significant figures.

Answers

Answer:

a. pH = 7.0

b. pH = 12.52

c. pH = 12.70

d. pH = 12.78

Explanation:

a. Deionized water has the [H⁺] of pure water = 1x10⁻⁷ (Kw = 1x10⁻¹⁴ = [H⁺][OH⁻] - [H⁺] = [OH⁻ -)

pH = -log[H⁺] = 7

b. Moles NaOH = 5x10⁻³L * (0.10mol / L) = 5x10⁻⁴moles OH⁻ / 0.015L = 0.0333M = [OH⁻]

-Total volume = 10mL+5mL = 15mL = 0.015L

pOH = -log[OH⁻] = 1.48

pH = 14-pOH

pH = 12.52

c. Moles NaOH = 0.010L * (0.10mol / L) = 1x10⁻³moles OH⁻ / 0.020L = 0.0500M = [OH⁻]

-Total volume = 10mL+10mL = 20mL = 0.020L

pOH = -log[OH⁻] = 1.30

pH = 14-pOH

pH = 12.70

d. Moles NaOH = 0.015L * (0.10mol / L) = 1.5x10⁻³moles OH⁻ / 0.025L = 0.060M = [OH⁻]

-Total volume = 10mL+15mL = 25mL = 0.025L

pOH = -log[OH⁻] = 1.22

pH = 14-pOH

pH = 12.78

Which change represents an oxidation reaction?

Answers

Here is the answer. (E) F e + Cu2^+^ — Fe^2+^ + Cu

An empty steel container is filled with 2.0 atm of H₂ and 1.0 atm of F₂. The system is allowed to reach equilibrium according to the reaction below. If Kp = 0.45 for this reaction, what is the equilibrium partial pressure of HF?

Answers

The equilibrium partial pressure of HF is 0.55 atm.

The equation of the reaction is;

        H2(g) + F2(g) ⇄ 2HF

I         2           1             0

C       -x           -x            +x

E     2 - x        1 - x           x

We know that;

pH2 = 2.0 atm

PF2 =  1.0 atm

pHF = ??

Kp = 0.45

So;

Kp = (pHF)^2/pH2. pF2

0.45 = x^2/(2 - x) (1 - x)

0.45 =  x^2/x^2 - 3x + 2

0.45(x^2 - 3x + 2) = x^2

0.45x^2 - 1.35x + 0.9 =  x^2

0.55 x^2 + 1.35x - 0.9 = 0

x = 0.55 atm

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What enzyme catalyses the reaction of PRPP transfer to hypoxanthine with
formation of IMP?

Answers

Answer:

HPRT

Explanation:

HPRT catalyzes the salvage reactions of hypoxanthine and guanine with PRPP to form IMP and GMP

The formation of GMP from IMP requires oxidation at C-2 of the purine ring, followed by a glutamine-dependent amidotransferase reaction that replaces the oxygen on C-2 with an amino group to yield 2-amino,6-oxy purine nucleoside monophosphate, or as this compound is commonly known, guanosine monophosphate.

Use the solubility rules from the Lab 4 introduction and your knowledge of qualitative separation schemes from the lab to answer the following questions. The qualitative analysis experiment you did is actually an abbreviated version of a much larger analysis scheme in which many different cations are separated and identified. Suppose a mixture contains Ag , K , NH4 , Hg22 , Pb2 , Mg2 , Sr2 , Ba2 , Cu2 , Al3 and Fe3 .
(a) Which of the following ions could you separate, by causing them to precipitate, with the addition of HCl?
Ag+ K+ NH4+
Hg22+ Pb2+ Mg2+
Sr2+ Ba2+ Cu2+
Al3+ Fe3+
(b) After the addition of HCl, the above sample is centrifuged and decanted. Which of the following cations remaining in the supernatant could you separate, by causing them to precipitate, with the addition of H2SO4? (Hint: H2SO4 is a source of sulfate ions. Select all that apply.)
Ag+ K+ NH4+
Hg22+ Pb2+ Mg2+
Sr2+ Ba2+ Cu2+
Al3+ Fe3+

Answers

Answer:

a13+a13

Explanation:

How many atoms are in 90.43 moles of copper

Answers

409 g P2O5 2) 5.44 x 1025 atoms Cu

Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, 8.12×10²³ atoms are in  90.43 mole of copper.

What is mole?

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity of amount of substance. It measure the number of elementary entities of a given substance that are present in a given sample. There are so many formula for calculating mole.

we know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number

number of atoms/molecules=number of moles × 6.022×10²³(Avogadro number)

number of moles of copper=90.43 moles

Substituting all the given values in the above equation, we get

number of atoms/molecules= 90.43 × 6.022×10²³

number of atoms/molecules=8.12×10²³ molecules

Therefore, 8.12×10²³ atoms are in 90.43 mole of copper.

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4. What is the specific heat of a substance if 5800 joules is
released in a 250 gram sample that will cool the substance from
60 degrees to 45 degrees?

Answers

Answer: 23.2

Explanation:

At what minimum temperature do rocks melt into lava?
A) 3,500 degrees Celsius
B) 6,332 degrees Fahrenheit
C) 800 degrees Fahrenheit
OD 800 degrees Celsius

Answers

The answer is D 800 degrees Celsius

what is the structure of methane​

Answers

Answer:

CH4

Explanation:

if it is wrong, i blame my brain

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