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3 years ago

What is the density of object A? Does it sink or float in water?

Chemistry

1 answer:

Oksana_A [137]3 years ago

3 0

Answer:

~1.5 g/cm3 and it does NOT float in water.

Explanation:

If you look at the graph, Object A weighs ~6 grams and is ~4 cm3 in volume

Density = Mass/Volume

So 6 grams/4 cm3 = 1.5 g/cm3

Water has a density of 1 g/cm3 and because Object A density is higher than that of water, it sinks.

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What does the VSEPR theory describe?

sweet-ann [11.9K]

Answer: it is C, why molecules have different shapes.

Explanation:

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3 years ago

Different between organic fertilizer and inorganic fertilizer

Svetradugi [14.3K]

Organic fertilizers are made from mined rock minerals, and natural plant and animal materials. They include ingredients like manure, guano, dried and powdered blood, ground bone, crushed shells, finely pulverized fish, phosphate rock, and wood.

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3 years ago

Read 2 more answers

7)What mass of hydrogen gas is produced when 8.56grams of lithium reacts with water to also produce lithium

Gnom [1K]

i guess this is the answer .

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2 years ago

The use of existing information in books, articles, and electronic databases is known as Group of answer choices Primary researc

BARSIC [14]

Answer:

Secondary research

Explanation:

Secondary research involves using already existing data, like what can be found in in books, articles, and electronic databases.

A is wrong. Primary research is the research that you do to obtain new information, as in experiments or in interviews and surveys.

B is wrong. Qualitative research is the gathering of non-numerical data.

C is wrong. Summative research is done at the end of a project to determine its success. It can also point the way to future research projects.

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3 years ago

A 1-liter solution contains 0.494 M hydrofluoric acid and 0.371 M potassium fluoride. Addition of 0.408 moles of hydrochloric ac

UkoKoshka [18]

Answer:

Option f: an addition of HCl will exceed the buffer capacity. The option d is also correct since it is a consequence of the option f.

Explanation:

The pH of the buffer solution before the addition of HCl is:

$pH = pKa + log(\frac{[KF]}{[HF]})$

$pH = -log(6.8 \cdot 10^{-4}) + log(\frac{0.371}{0.494}) = 3.04$

The hydrochloric acid added will react with the potassium fluoride as follows:

H₃O⁺(aq) + F⁻(aq) ⇄ HF(aq) + H₂O(l)

The number of moles (η) of potassium fluoride (KF) and the HF before the addition of HCl is:

$\eta_{KF}_{i} = C_{KF}*V = 0.371 M*1 L = 0.371 mol$

$\eta_{HF}_{i} = C_{HF}*V = 0.494 M*1 L = 0.494 moles$

The number of moles of the HCl added is 0.408 moles. Since the number of moles of HCl is bigger thant the number of moles of KF, the moles of HCl that remains after the reaction is:

$\eta_{HCl} = \eta_{HCl} - \eta_{KF}_{i} = 0.408 moles - 0.371 moles = 0.037 moles$

Hence, the KF is totally consumed after the reaction with HCl and thus, exceding the buffer capacity.

We can calculate the pH after the addition of HCl:

HF(aq) + H₂O(l) ⇄ F⁻(aq) + H₃O⁺(aq) (1)

The number of moles of HF after the reaction of KF with HCl is:

$\eta_{HF} = 0.494 moles + (0.408 moles - 0.371 moles) = 0.531 moles$

And the concentration of HF after the reaction of KF with HCl is is:

$C_{HF} = \frac{\eta_{HF}}{V} = \frac{0.531 moles}{1 L} = 0.531 moles/L$

Now, from the equilibrium of equation (1) we have:

$Ka = \frac{[H_{3}O^{+}][F^{-}]}{[HF]}$

$Ka = \frac{x^{2}}{0.531 - x}$ (2)

By solving equation (2) for x we have:

x = 0.0187

Finally, the pH after the addition of HCl is:

$pH = -log (H_{3}O^{+}) = -log (0.0187) = 1.73$

Therefore, the addition of HCl will exceed the buffer capacity and thus, lower the pH by several units. The correct option is f: an addition of HCl will exceed the buffer capacity. The option d is also correct since it is a consequence of the option f.

I hope it helps you!

8 0

4 years ago