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3 years ago

15

3 characteristics of chemical change

2 answers:

Doss [256]3 years ago

6 0

Answer: in chemical changes, usually new substances are formed. Signs of chemical changes are change of colour, temperature and formation of precipitation

gtnhenbr [62]3 years ago

3 0

Answer:

A physical change involves a change in physical properties. Examples of physical properties include melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density.

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Pls help. This is about heat. I got the answer, just need the working

Mars2501 [29]

Answer:

See below

Explanation:

You have to heat the calorimeter to 100 C from 20 C

this will take .20 kg * 390 j /kg-C * 80 C = <u>6240 j</u>

You have to heat the mass of water to boiling point (100 C ) from 20C

this will take

.50 kg * 4182 j/kg-C * 80 = <u>167,280 j </u>

AND you have to add enough heat to boil off .03 kg of water:

.03 kg * (2260000 j/kg-C ) =<u> 67,800 j</u>

<u />

Power = joules / sec = (6240 + 167280 + 67800) / 274.8 =<u> 878 watts </u>

<u />

<u>Your answer may differ just a bit for slightly different or rounded values of specific heat or heat of fusion for water .....</u>

7 0

2 years ago

If 0.035pC of charge is transferred via the movement of Al3+ ions, how's many of these must be transferred in total? Please add

mr Goodwill [35]

Each $Al^+^3$ ion contains three extra protons. Hence, the extra charge on each $Al^+^3$ = $3 \times 1.6 \times 10^-^1^9$ C

Total charge = 0.035 pC

Total charge (Q) = $0.035 \times 10^-^1^2$ C

Let the number of $Al^+^3$ ions be n.

According to question:

$n \times 3 \times 1.6 \times 10^-^1^9 =0.035 \times 10^-^1^2$

$n = \frac{0.035 \times 10^-^1^2}{3 \times 1.6 \times 10^-^1^9}$

$n = 7.29167 \times 10^4$

n = 72917

Hence, the total number of ions needed to be transferred is 72917

3 0

3 years ago

:)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))

FromTheMoon [43]

Good morning dear...

Have a beautiful and joyful day ahead.

6 0

2 years ago

Define couple and give 2 examples

Elodia [21]

Answer:

Two equal and opposite parallel forces not acting along the same line, form a couple. A couple is always needed to produce the rotation.

For example, turning a key in a lock and turning a steering wheel.

3 0

2 years ago

Read 2 more answers

Which of the following is the largest unit?<br> Hectogram<br> Dekagram<br> Decigram<br> Microgram

MAXImum [283]

Answer:

So far it seems that hectogram us the largest unit.

Dekagram is a metric unit of mass or weight, equal to 10 grams.

Hectogram is a metric unit of mass equal to 100 grams.

Decigram is a metric unit of mass and weight equal to ¹/₁₀ gram.

Microgram is a metric unit of mass equal to one millionth of a gram.

8 0

3 years ago