All categories

3 years ago

Why is ice melting a physical change?

2 answers:

6 0

As an ice cube melts, its shape changes as it acquires the ability to flow. However, its composition does not change. Melting is an example of a physical change .

Oksana_A [137]3 years ago

4 0

Answer:

Explanation:

The atoms in the ice are just speeding up to turn into water, the molecules and atoms themselves don't change at all

You might be interested in

If acetic acid is the only acid that vinegar contains (ka=1.8×10−5), calculate the concentration of acetic acid in the vinegar.

kicyunya [14]

Ethanoic (Acetic) acid is a weak acid and do not dissociate fully. Therefore its equilibrium state has to be considered here.

$CH_{3}COOH \ \textless \ ---\ \textgreater \ H^{+} + CH_{3}COO^{-}$

In this case pH value of the solution is necessary to calculate the concentration but it's not given here so pH = 2.88 (looked it up)

pH = 2.88 ==> $[H^{+}]$ = $10^{-2.88}$ = 0.001 $moldm^{-3}$

The change in Concentration Δ $[CH_{3}COOH]$ = 0.001 $moldm^{-3}$

  CH3COOH H+ CH3COOH
Initial   $moldm^{-3}$      $x$ 0 0

Change $moldm^{-3}$ -0.001 +0.001 +0.001

Equilibrium $moldm^{-3}$ $x$ - 0.001 0.001 0.001


Since the $k_{a}$ value is so small, the assumption
$[CH_{3}COOH]_{initial} = [CH_{3}COOH]_{equilibrium}$ can be made.

$k_{a} = [tex]= 1.8*10^{-5} = \frac{[H^{+}][CH_{3}COO^{-}]}{[CH_{3}COOH]} = \frac{0.001^{2}}{x}$

Solve for x to get the required concentration.

note: 1.)Since you need the answer in 2SF don&t round up values in the middle of the calculation like I've done here.

2.) The ICE (Initial, Change, Equilibrium) table may come in handy if you are new to problems of this kind

Hope this helps!

8 0

3 years ago

1.Explain why the reactivity of group 7 decreases as you move down the group. Try to use the sentence starters here: When group

Kruka [31]

Answer: The reactivity of group 7 decreases as we move down the group because:

Explanation:

The elements of group 7 that is fluorine to iodine. The halogens are non metals and they react with metals to gain electrons. The metals loose electrons and the non metal gains it.

As we move down the group the atomic radius gets bigger( more electron and more proton) and as a result the outer shells move further away from the nucleus.

There is more distance between the negatively charged electrons and positively charged nucleus.

Therefore the force of attraction between the shells and nucleus is lesser or weaker.

This makes attracting an extra electron from metals very difficult which results in weaker reaction.

Consequently, the reactivity decreases as we move down the group 7

5 0

3 years ago

29. If a walnut is burned in a

harkovskaia [24]

Energy were released from the walnut, q = 1,673.6 J

<h3>Equation :</h3>

To find the energy using formula,

q = mcΔt

where,

q is charge

m is mass

c is specific heat of water

Δt is change in temperature

So, given

t₁ = 50°C

t₂ = 60°C

m = 40g

c = 4.184 J/g

Now putting the values known,

We get,

q = mc(t₂ - t₁)

q = 40g x 4.184 J/g x (60 - 50)

q = 167.36 J x 10

q = 1,673.6 J

<h3>What is heat energy?</h3>

Heat is the thermal energy that is transferred when two systems with different surface temperatures come into contact. Heat is denoted by the letters q or Q and is measured in Joules.

To know more about specific heat :

brainly.com/question/11297584

#SPJ9

8 0

1 year ago

what are the moon phases. but be more detailed and don't put in "the phases of the moon" be more detailed.

Murrr4er [49]

Explanation:

The lunar phase or Moon phase is the shape of the Moon's directly sunlit portion as viewed from Earth. The lunar phases gradually change over a synodic month as the Moon's orbital positions around Earth and Earth around the Sun shift.

4 0

3 years ago

Read 2 more answers

The oxidation number of all the element in free state is 0

Art [367]

Answer:

Zero-Nine

Explanation:

this is becasue these numbers are rather small and if you plug these numbers into an equation you will most likely get 0.

8 0

3 years ago