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Delicious77 [7]
3 years ago
13

What is an element considered a pure substance?

Chemistry
1 answer:
Alona [7]3 years ago
8 0

A compound is a pure substance composed of two or more different atoms chemically bonded to one another. A compound can be destroyed by chemical means. It might be broken down into simpler compounds, into its elements or a combination of the two.


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How can I find the velocity?
34kurt

Answer:

The formula for velocity is v = Δs/Δt

Explanation:

Velocity equals change in speed divided by change in time.

3 0
3 years ago
Read 2 more answers
Which missing item would complete this alpha decay reaction?<br><br> 257/100 Fm= ________+4/2He
maria [59]

Answer: ₉₈²⁵³Cf

253 is a superscript to the left of the symbol, Cf, which represents the mass number, and 98 is a subscript to the left of the same symbol, which represents the atomic number.

Explanation:

1) The alpha decay equation shows that the isotope Fm - 257, whose nucleus has 100 protons and 157 neutrons, emitted an alpha particle (a nucleus with 2 protons and 2 neutrons).

2) Therefore:

i) the mass number decreased in 4, from 257 to 257 - 4 = 253.

2) the atomic number decreased in 2, from 100 to 100 - 2 = 98.

3) Hence the formed atom has atomic number 98, which is californium, Cf, and the isotope is californium - 253.

4) The item that completes the given alpha decay reaction is:

₉₈²⁵³ Cf.

5) The complete alfpha decay reaction is:

₁₀₀²⁵⁷ Fm → ₉₈²⁵³Cf + ₂⁴He

You can verify the mass balance:

257 = 253 + 4, and

100 = 98 + 2

4 0
3 years ago
Read 2 more answers
Nitric acid (HNO3) is a strong acid that is completely ionized in aqueous solutions of concentrations ranging from 1% to 10% (1.
Alborosie

<u>Given:</u>

Concentration of HNO3 = 7.50 M

% dissociation of HNO3 = 33%

<u>To determine:</u>

The Ka of HNO3

<u>Explanation:</u>

Based on the given data

[H+] = [NO3-] = 33%[HNO3] = 0.33*7.50 = 2.48 M

The dissociation equilibrium is-

            HNO3   ↔    H+      +      NO3-

I            7.50               0                 0

C          -2.48          +2.48              +2.48

E            5.02            2.48              2.48

Ka = [H+][NO3-]/HNO3 = (2.48)²/5.02 = 1.23

Ans: Ka for HNO3 = 1.23

6 0
3 years ago
A strong acid can also be described as a very weak .
faltersainse [42]
I guess is weak alkaline. when the substance is more acidic, there will be less alkalinity
4 0
3 years ago
Draw the product that valine forms when it reacts with excess CH3CH2OH and HCl followed by a wash with aqueous base.
-BARSIC- [3]

Answer:

Product: ethyl L-valinate

Explanation:

If we want to understand what it is the molecule produced we have to an<u>alyze the reagents</u>. We have valine an <u>amino acid</u>, in this kind of compounds we have an <em>amine group</em> (NH_2) and a <em>carboxylic acid</em> group (COOH).  Additionally, we have an <u>alcohol </u>(CH_3CH_2OH) in the presence of HCl (a <u>strong acid</u>) in the first step, and a base (OH^-).

When we have an acid and an alcohol in a vessel we will have an <u>esterification reaction</u>. In other words, an ester is produced. As the <em>first step,</em> the oxygen in the C=O (in the carboxylic acid group) would be protonated. In the <em>second step</em>, the ethanol attacks the carbon in the C=O of the carboxylic acid group producing a new bond between the oxygen in the ethanol and the carbon in the carboxylic acid. In <em>step 3</em>, a proton is transferred to produce a better leaving group (H_2O). In <em>step 4</em>, a water molecule leaves the main structure to produce again the double bond C=O. <em>Finally</em>, a base (OH^-) removes the hydrogen from the C=O bond to produce ethyl L-valinate

See figure 1

I hope it helps!

7 0
3 years ago
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