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3 years ago

Physical and chemical change

2 answers:

5 0

physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed. For example, if a piece of paper is cut up into small pieces it still is paper.

lina2011 [118]3 years ago

5 0

Chemical change: a change that occurs when one substance combines with another substance to make a new substance

Physical change: a change to any physical property of a substance

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True or False: You can make a concentrated solution more dilute by adding solvent.

Vlad [161]

That statement is true because to make a diluted solution, you have to add more solvent than the solute in a concentrated solution. This is extra information, but to make a diluted solution more concentrated, you have to add more solute since a concentrated solution has an excess amount of solute as stated before.

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3 years ago

Read 2 more answers

Calculate Density:<br> Volume=13cm3, Mass=147.55g<br> Someone please help

almond37 [142]

Answer:

11.35 g/cm³

Explanation:

If your rounding then 11.4. hope this helps :)

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2 years ago

The teal line of the hydrogen emission spectrum has a wavelength of 486.0 nm. A hydrogen emission spectrum has a violet, a blue,

Sloan [31]

Answer:

The correct answer to the following question will be "4.08 × 10⁻¹⁹ Joule".

Explanation:

Given:

Wavelength, λ = 486.0 nm

As we know,

$E=h\upsilon =\frac{hc}{\lambda}$

On putting the estimated values, we get

⇒ $=\frac{1241.5 \ ev\ nm}{486 \ nm}$

⇒ $=2.554 \ ev$

∴ 1 ev = 1.6 × 10⁻¹⁹ J

Now,

Energy, $E=2.554\times 1.6\times 10^{-19}$

⇒ $=4.08\times 10^{-19} Joule$

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3 years ago

If 6.0 x 10^23 atoms of aluminum weigh 27 g, calculate the mass of 1 atom of aluminum in picograms.

Georgia [21]

Answer:

$4.5 \times 10^{ - 11}$ picograms

Explanation:

Please see attached picture for full solution.

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3 years ago

For the hypothetical reaction: A + B ---> 2C, write an expression that relates the disappearance of A and B to the appearance

forsale [732]

Answer:

Rate expression has been given below

Explanation:

According to the given equation, 1 molecule of A reacts with 1 molecule of B and produces 2 molecules of B at a time.

So, rate of disappearance of both A and B are one half of rate of appearance of B

Hence rate expression can be represented as:

$Rate=\frac{-\Delta [A]}{\Delta t}=\frac{-\Delta [B]}{\Delta t}=\frac{1}{2}\frac{\Delta [C]}{\Delta t}$

where $\frac{-\Delta [A]}{\Delta t}$ is rate of disappearance of A, $\frac{-\Delta [B]}{\Delta t}$ is rate of disappearance of B and $\frac{\Delta [C]}{\Delta t}$ rate of appearance of C

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3 years ago