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2 years ago

Identify the TRUE statement.

Chemistry

1 answer:

xeze [42]2 years ago

4 0

Answer:

d. In a granite containing quartz, mica, and feldspar, everything weathers to clay except the quartz.

Explanation:

Granite is a rock formed by a set of minerals, but its composition is basically as follows: Quartz, a colorless mineral; Feldspar (orthoclase, sanidine and microcline), responsible for the variety of colors, including reddish, pink and cream-gray; and Mica (biotite and muscovite), which adds shine to the rock. Of these three minerals, mica and feldspar generate clay during the weathering process, however quartz does not generate clay, probably due to its hardness.

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Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture. K pKa1 K pKa2 1.30

FrozenT [24]

Answer:

* Before addition of any KOH:

pH = 0,0301

*After addition of 25.0 mL KOH:

pH = 1,30

*After addition of 50.0 mL KOH:

pH = 2,87

*After addition of 75.0 mL KOH:

pH = 6,70

*After addition of 100.0 mL KOH:

pH = 10,7

Explanation:

H₃PO₃ has the following equilibriums:

H₃PO₃ ⇄ H₂PO₃⁻ H⁺

k = [H₂PO₃⁻] [H⁺] / [H₃PO₃] k = 10^-(1,30) (1)

H₂PO₃⁻ ⇄ HPO₃²⁻ + H⁺

k = [HPO₃²⁻] [H⁺] / [H₂PO₃⁻] k = 10^-(6,70) (2)

Moles of H₃PO₃ are:

0,0500L×(1,8mol/L) = 0,09 moles of H₃PO₃

* Before addition of any KOH:

Using (1), moles in equilibrium are:

H₃PO₃: 0,09-x

H₂PO₃⁻: x

H⁺: x

Replacing:

$10^{-1.30} = \frac{x^2}{0.09-x}$

4.51x10⁻³ - 0.050x -x² = 0

The right solution of x is:

x = 0.0466589

As volume is 0,050L

[H⁺] = 0.0466589moles / 0,050L = 0,933M

As pH = -log [H⁺]

pH = 0,0301

*After addition of 25.0 mL KOH:

0,025L×1,8M = 0,045 moles of KOH that reacts with H₃PO₃ thus:

KOH + H₃PO₃ → H₂PO₃⁻ + H₂O

That means moles of KOH will be the same of H₂PO₃⁻ and moles of H₃PO₃ are 0,09moles - 0,045moles = 0,045moles

Henderson-Hasselbalch formula is:

pH = pka + log₁₀ [A⁻] /[HA]

Where A⁻ is H₂PO₃⁻ and HA is H₃PO₃.

Replacing:

pH = 1,30 + log₁₀ [0,045mol] / [0,045mol]

pH = 1,30

*After addition of 50.0 mL KOH:

The addition of 50.0 mL KOH consume all H₃PO₃. Thus, in the solution you will have just H₂PO₃⁻. Thus, moles in solution for the equilibrium will be:

H₂PO₃⁻: 0,09-x

HPO₃²⁻: x

H⁺: x

Replacing:

$10^{-6.70} = \frac{x^2}{0.09-x}$

1.8x10⁻⁸ - 2x10⁻⁷x - x² = 0

The right solution of x is:

x = 0.000134064

As volume is 50,0mL + 50,0mL = 100,0mL

[H⁺] = 0.000134064moles / 0,100L = 1.34x10⁻³M

As pH = -log [H⁺]

pH = 2,87

*After addition of 75.0 mL KOH:

Applying Henderson-Hasselbalch formula you will have 0,045 moles of both H₂PO₃⁻ HPO₃²⁻ and pka: 6,70:

pH = 6,70 + log₁₀ [0,045mol] / [0,045mol]

pH = 6,70

*After addition of 100.0 mL KOH:

You will have just 0,09moles of HPO₃²⁻, the equilibrium will be:

HPO₃²⁻ + H₂O ⇄ H₂PO₃⁻ + OH⁻ with kb = kw/ka = 1x10⁻¹⁴/10^-(6,70) = 5,01x10⁻⁸

kb = [H₂PO₃⁻] [OH⁻] / [HPO₃²⁻]

Moles are:

H₂PO₃⁻: x

OH⁻: x

HPO₃²⁻: 0,09-x

Replacing:

$5.01x10^{-8} = \frac{x^2}{0.09-x}$

4.5x10⁻⁹ - 5.01x10⁻⁸x - x² = 0

The right solution of x is:

x = 0.000067057

As volume is 50,0mL + 100,0mL = 150,0mL

[OH⁻] = 0.000067057moles / 0,150L = 4.47x10⁻⁴M

As pH = 14-pOH; pOH = -log [OH⁻]

pH = 10,7

I hope it helps!

6 0

2 years ago

A 0.941 gram piece of magnesium metal is heated and reacts with oxygen. the resulting oxide weighed 1.560 grams. determine the p

Whitepunk [10]

Given:

magnesium = 0.941 gram piece

Magnesium oxide= 1.560 grams

Formula:

(magnesium / magnesium oxide) x 100 = % Mg

100% - % Mg = percent composition of each element

Solution:

(0.941g Mg) / (1.560g MgO)

= 0.603

= 60.3% Mg

100% - 60.3%

= 39.7%

39.7% is the percentage composition of each element.

5 0

2 years ago

Consider the complex ion [CO(NH3)6]3+. Which response contains all of the following statements that are true, and no false state

Alja [10]

Answer:

III, IV, and V

Explanation:

The complex [CO(NH3)6]3+ is a diamagnetic complex. It a low spin d^6 complex. Most d^6 complexes are low spin due to the higher crystal field stabilization energy of the low spin over the high spin arrangement.

d^6 metal complexes are known to be octahedral (a coordination number of 6 leads to octahedral geometry). Octahedral complexes does not have geometric isomers rather, may exist as the fac or her stereo isomers.

8 0

2 years ago

Describe how transpiration and respiration show interactions among Earth's system

stepladder [879]

Earth has 4 systems/ spheres which are known as Lithosphere(land), Biosphere(living things), Hydrosphere(water) and Atmosphere(air).

Transpiration is the process that interact with the Hydrosphere and Respiration is the process that interacts with the Atmosphere.

Transpiration is the process happening in plants which absorb and distribute water through their roots and release water in the form of vapors through their leaves. As this process involves Water, therefore this process interacts with the Hydrosphere.

Respiration is the process in which plants convert carbon dioxide to oxygen as a part of photosynthesis which was then inhaled by the animals. As this process involves Air, therefore this process interacts with the Atmosphere.

7 0

2 years ago

Read 2 more answers

When the Modern Museum of Art separated its consumers by whether they were culture-oriented or outdoor-oriented for its new exhi

madam [21]

Answer:

A. psychographic lifestyle segmentation

Explanation:

Psychographic lifestyle segmentation -

It refers to the distribution or classification method , where the consumers of a particular goods and services are classified into particular groups , depending on the psychological characteristics of the consumers , is referred to as psychographic lifestyle segmentation .

The segmentation take care of the consumers celief , priority , va;ues , decision - making process , lifestyle .

The method enables to market the goods and services in a better manner , nd increases the profit of the company .

Hence , from the given scenario of the question ,

The correct option is A. psychographic lifestyle segmentation .

8 0

2 years ago