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3 years ago

Which of these is an example of a physical change? A) iron melting B) steel rusting C) paper burning Eliminate D) wood decaying

2 answers:

7 0

A) iron melting is the only example of physical change, because it's just a change of state (from solid to liquid).
The others, rusting, combustion, and decay are all chemical changes, because it will result in changing the chemical bonds between the atoms.

Mazyrski [523]3 years ago

5 0

Its iron melting i made an 100% on the test

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1. In an equilibrium experiment, acetic acid (which is a weak acid) is mixed with sodium acetate (a soluble salt), with methyl o

koban [17]

Explanation:

It is known that acetic acid is a weak acid. It's equilibrium of dissociation will be represented as follows.

$CH_{3}COOH(aq) + H_{2}O(l) \rightleftharpoons CH_{3}COO^{-}(aq) + H_{3}O^{+}(aq)$

On the other hand, sodium acetate ( $CH_{3}COONa$ ) is a salt of weak acid, that is, $CH_{3}COOH$ and strong base, that is, NaOH. Therefore, aqueous solution of sodium acetate will be basic in nature.

Since, acetic acid is a weak acid but still it is an acid. So, when methyl orange is added in a solution of acetic acid then it given a reddish-orange color because of its acidity.

When sodium acetate is mixed into this solution then it will dissociate as follows.

$CH_{3}COO^{-}Na^{+}(aq) \rightleftharpoons CH_{3}COO^{-}(aq) + Na^{+}(aq)$

As both solutions are liberating acetate ion upon dissociation. Hence, it is the common ion.

So, when more acetate ions will increase from dissociation of sodium acetate the according to Le Chatelier's principle the equilibrium will shift on left side.

As a result, there will be decrease in the concentration of hydronium ions. As a result, there will be increase in the pH of the system.

Hence, color of methyl orange will change from reddish orange to yellow. This shift in equilibrium is due to the common ion which is $CH_{3}COO^{-}$ ion.

4 0

3 years ago

What mass of water will change its temperature by 3.0 0C when 525 J of heat is added to it? The specific heat of water is 4.184

pav-90 [236]

Answer:

Mass of water = 41.8 g

Explanation:

Given data:

Mass of water = ?

Change in temperature = 3.0 °C

Specific heat capacity = 4.184 j/g.°C

Heat absorbed = 525 j

Solution:

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 3.0°C

Now we will put the values in formula.

525 J = m × 4.184 j/g.°C × 3.0°C

525 J = m × 12.552 j/g

m = 525 J/ 12.552 j/g

m = 41.8 g

4 0

3 years ago

Are these gases lighter than or denser than air? How can you tell?

kotegsom [21]

Some Gases are lighter than air
Remember,Air is a mixture of gases
So you cant tell!
It depends on the gas
Hope i helped

3 0

3 years ago

Which electron configuration of the 4f energy sublevel is most stable?

umka21 [38]

Answer: both options A and D

Explanation:

Half filled and completely filled orbitals are more stable than any other configuration since they are more symmetrical and energy exchange Occurs readily.

So 4f^7& 4f^14 are more stable

7 0

3 years ago

What quantity of heat is transferred when a 150.0g block of iron metal is heated from 25.0°C to 73.3°C? What is the direction of

s344n2d4d5 [400]

The direction of heat flow is increased which means blocks temperature is higher and hotter than it was before

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3 years ago