8.3 miles of sodium chloride in 0.65 of water.

In terms of valence electrons, explain why metals form positive ions.

diamong [38]

Answer:

Explanation:

Metal elements form positively charged ions called cations because they are located on the left side of the periodic table These elements all have valence electrons in an s orbital. These electrons are relatively easy for the atom to lose to achieve a stable octet of electrons in its outermost energy shell.

8 0

3 years ago

Rank these acids according to their expected pKa values.

givi [52]

Answer:

According to their expected pKa values, the order of those acids should be:

1- Cl2CHCOOH is the strongest acid and the lowest pKa.

2- ClCH2COOH is a strong acid, but no more than the first. Medium pKa value.

3- ClCH2CH2COOH is a strong acid, but no more than the two previous acids. High pKa value.

4- CH3CH2COOH is the weakest acid, so the highest pKa value.

Explanation:

The pKa values are the negative logarithm of dissociation constant. It represents the relative strengths of the acids. Stronger acids show smaller pKa values and weak acids present larger pKa value. The stronger the acid, the weaker it's the conjugate base. The larger the pKa of the conjugate base, the stronger the acid. The strength of an acid is inversely related to the strength of its conjugate.

Conjugate bases are the substance that has one less proton than the parent acid. The conjugate base of the acid presented in the problem are:

ClCH2COOH -> ClCH2COO- + H+

ClCH2CH2COOH -> ClCH2CH2COO- + H+

CH3CH2COOH -> CH3CH2COO- + H+

Cl2CHCOOH -> Cl2CHCOO - + H+

Cl2CHCOOH. The negative charge presented on its conjugate base is by resonance and inductive effect. This is the strongest acid.

ClCH2COOH. A negative charge is stabilized by resonance and electron-withdrawing but only one atom is present. So this acid is less strong than the first one.

ClCH2CH2COOH. The negative charge is stabilized by resonance and electron-withdrawing atom but the effect is less compared to the two acids showed previously.

CH3CH2COOH. The negative charge is stabilized by resonance and destabilized due to CH3 group. This is the weakest acid among the problem.

Stronger acids have smaller pKa values and weak acids have larger pKa values. Due to the information present in this problem, Cl2CHCOOH is the strongest acid and the lowest pKa. CH3CH2COOH is the weakest acid, so the highest pKa value.

Finally, we can conclude that according to their expected pKa values, the order of those acids should be:

1- Cl2CHCOOH is the strongest acid and the lowest pKa.

2- ClCH2COOH is a strong acid, but no more than the first. Medium pKa value.

3- ClCH2CH2COOH is a strong acid, but no more than the two previous acids. High pKa value.

4- CH3CH2COOH is the weakest acid, so the highest pKa value.

3 0

3 years ago

What can the student predict if she finds the mass of the whole candy bar, including the wrapper?

Vesna [10]

Answer:

A student can predict Amount of calories present if she finds the mass of whole candy bar,including the wrapper.

Explanation:

Based on the mass of a whole candy bar a student can predict the calories contained in the candy bar. If the mass of candy bar is more than it means it has more calories and if the candy bar has less mass than it shows the presence of fewer calories.

More calories mean more sugar content in the candy bar. With sugar, the candy bar has carbohydrates also. The sugar present in the bar gives us energy.

6 0

3 years ago

A sample originally contained 1.28 g of a radioisotope. It now contains 1.12 g of its daughter isotope.

dexar [7]

The answer is 3.

The relation between number of half-lives (n) and decimal amount remaining (x) can be expressed as:

 $(1/2) ^{n} =x$

We need to calculate n, but we need x to do that. To calculate what percentage of a radioactive species would be found as daughter material, we must calculate what amount remained:
1.28 - 1.12 = 0.16

If 1.28 is 100%, how much percent is 0.16:
1.28 : 100% = 0.16 : x
x = 12.5%
Presented as decimal amount:
x = 0.125

Now, let's implement this in the equation:

 $(1/2) ^{n} =0.125$

Because of the exponent, we will log both sides of the equation:
$n * log(1/2) = log(0.125)$
$n = \frac{log(0.125)}{log(1/2)}$
 $n = \frac{log(0.125)}{log(0.5)}$
 $n= \frac{-0.903}{-0.301}$
$n = 3$

Therefore, 3 half-lives have passed since the sample originally formed.

4 0

3 years ago

Read 2 more answers

The different phases of the Moon refer to A. Changes in the Moon's shape. B. Changes in the Moon's visibility. C. Changes in sea

Sav [38]

Answer:

B. Changes in the Moon's visibility.

Explanation:

The moon's shifting of position makes it "appear" as being smaller or bigger. This is simply because the moon is rotating and the sun's light shines on a certain area of the moon, and depending on where we are on the Earth is how the moon looks or appears to our perspective.

5 0

3 years ago