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3 years ago

Physical Changes

1 answer:

7 0

C. Physical changes do not change the identity of a substance, only the physical appearance such as shape or form. If you break a pencil in half, it is still composed of the same material and therefore keeps its identity as the substance it was before the physical change. Phase changes, such as ice melting, is also a physical change because it changes form. But ice is still made of H20 just like water and steam are comprised of H20.

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What are the products of this chemical equation? HCl(aq) + NaOH(aq) →

rusak2 [61]

I believe it is NaCl(aq) + H2O

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2 years ago

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Explain why arginine is a basic amino acid

Mumz [18]

Answer:

There are three amino acids that have basic side chains at neutral pH. These are arginine (Arg), lysine (Lys), and histidine (His). Their side chains contain nitrogen and resemble ammonia, which is a base. Their pKa's are high enough that they tend to bind protons, gaining a positive charge in the process.

<h2>Hope it helps you.</h2>

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2 years ago

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What is the total number of grams of h2o produced when 22 grams of propane undergoes complete combustion?

SSSSS [86.1K]

The combustion reaction of propane would be expressed as:

C3H8 + 5O2 = 3CO2 + 4H2O

To determine the mass of water that is produced from the given amount of propane, we use the mass of propane and the relation of the substances from the balanced reaction. We do as follows:

moles propane = 22 g C3H8 ( 1 mol / 44.1 g ) = 0.50 mol C3H8
moles H2O = 0.50 mol C3H8 ( 4 mol H2O / 1 mol C3H8) = 2 mol H2O
mass H2O = 2 mol H2O ( 18.02 g / 1 mol ) = 36.04 g H2O

Therefore, the mass of water that is produced from 22 grams of propane would be 36.04 g.

5 0

2 years ago

John rings a doorbell.

Kamila [148]

Answer:

Explanation:

Remember, <u>Newton's third law of motion;</u> which says in part that <em>"Every action has an equal and opposite reaction."</em>

Hence, in this case, the fact that the doorbell rang out implies that there was another force that was exerted on it; which is, John's finger pressing the doorbell.

In other words, when John uses his fingers to press the doorbell button he applies a force (a mechanical force), and that force results in an opposite reaction; the ringing of the doorbell.

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2 years ago

Name two compounds with more exothermic lattice energies than scandium oxide and justify your choice.

N76 [4]

Answer:

1 . $Al_2O_3$

2. $TiO_2$

Explanation:

The more stable the ionic compound, the more is it lattice energy.

The more the charge on the cation and the anion, the greater is the lattice energy.
The less the size of the cation and the anion, the greater is the lattice energy.

Scandium oxide ( $Sc_2O_3$ ) is an oxide in which $Sc^{3+}$ behaves as cation and $O^{2-}$ behaves as anion.

The compounds which has higher lattice energy than scandium oxide are:

1 . $Al_2O_3$

This is because the charge are same on the cation and the anion as in the case of the Scandium oxide but the size of the cation $Al^{3+}$ is smaller than $Sc^{3+}$ . Thus, this corresponds to higher lattice energy.

2. $TiO_2$

This is because the charge on the cation $Ti^{4+}$ is greater than that of $Sc^{3+}$ and also the size of the cation $Ti^{4+}$ is smaller than $Sc^{3+}$ . Thus, this corresponds to higher lattice energy.

3 0

2 years ago