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3 years ago

Are phase changes physical or chemical changes? why?

2 answers:

Studentka2010 [4]3 years ago

6 0

Physical! Because they do not modify the nature of the substance ( if you look at the chemical level) and it is reversible

Vapor is H20
Water is H20
Ice is H20

A chemical changes is not reversible
Burning wood for example! And the reactants interact together to form a new product.

Reptile [31]3 years ago

3 0

<h2>Answer:</h2>

Physical changes

<h2>Example:</h2>

You added enough energy to create a phase change from solid to liquid. Physical actions, such as changing temperature or pressure, can cause physical changes. No chemical changes took place when you melted the ice. The water molecules are still water molecules.

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Which equation describes the process of photosynthesis?

Vedmedyk [2.9K]

Answer:

The FIRST option, give me brainliest answer pls

Explanation:

The photosynthesis equation is as follows: 6CO2 + 6H20 + (energy) → C6H12O6 + 6O2 Carbon dioxide + water + energy from light produces glucose and oxygen

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2 years ago

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You have three drinks in front of you. you know how they are made, but are unsure which one has the highest concentration of jui

GuDViN [60]

(I think) you would have to divided the number i dont know the exact answer but ya hope this help

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3 years ago

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820 g Li2SO4 is dissolved into 2500 mL of solution. What is the molar concentration?

Andreas93 [3]

Molarity is defined as the moles of solute per liter of solution. $M=\frac{n}{V}$ . Where M is molarity, n is the number of moles and V is the volume. First we must find the molar mass of $Li_2SO_4$ which is 109.98 g/mol

$Li_2SO_4= 2 \times Li_{Ar} + S_{Ar} + 4 \times O_{Ar}\\= (2 \times 6.941 + 32.1 + 4 \times 16.0) = 109.98 g/mol$

$820\ g\ Li_2SO_4 \times \frac{mol}{109.98\ g}= 7.46\ mol\ Li_2SO4$

Then we find the molarity using above equation

$M= \frac{n}{V} = \frac{7.46 mol}{2500ml} \times\frac{1000ml}{L} = 2.98\ M$

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4 years ago

In stoichiometric calculations, which quantity MUST be used to convert from one chemical substance to another?

Cloud [144]

The answer is

C) mole ratio

4 0

3 years ago

Which of the following statements regarding alpha particles are true? Check all that apply.a. Alpha particles have a mass number

egoroff_w [7]

Answer:

The only true statement is:

a. <u><em>Alpha particles have a mass number of 4</em></u>

Explanation:

<em>Alpha particles</em> are radiactive particles equivalent to a helium nucleus, so they have two protons and two neutrons.

Hence, alpha particles, α, are represented as:

⁴₂He

The superscript 4 to the left of the chemical symbol is the <em>mass number:</em> 2 protons + 2 neutrons = 4

The subscript 2 to the left of the chemical symbol is the atomic number: 2 protons = 2.

Hence, the statement "a. Alpha particles have a mass number of 4" is true.

As for the other statements, you have:

<em>b. Alpha particles have a nulear charge of +1:</em> <u>false</u>

Since, these particles are the nucleous of the helium atom, the nuclear charge equals the number of protons of this atom: +2. Hence, the statement is false.

c. <em>Alpha particle formation is accompanied by the conversion of a proton into a neutron</em> and d. <em>Alpha particle formation is accompanied by the conversion of a neutron into a proton</em>. <u>(both false</u>)

The conversion of a protons into a neutrons and the conversion of a neutron into a proton are product of other kind of radiactive desintegrations.

The conversion of a proton into a neutron involves the emission of a positron ( particle with same mass as the electron but positive charge) from the nucleus, which is represented as ⁰₊₁β.

The conversion of a neutron into a proton involves the emssion of an electron from the nucleus, which is the emission of a beta particle represented as ⁰₋₁β.

Therefore, these last two statements are also false.

4 0

3 years ago