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4 years ago

20 points

Chemistry

1 answer:

poizon [28]4 years ago

5 0

Answer:

1, 4, 1,5

Explanation:

1 PCl5 + 4 H2O → 1 H3PO4 + 5 HCl

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15.0 mL of an unknown clear liquid is added to a 50 mL graduated cylinder. The mass of the liquid is determined to be 12.7 grams

sveticcg [70]

Answer:

$\boxed {\tt A. \ d=0.85 \ g/mL}$

Explanation:

Density is found by dividing the mass by the volume.

$d=\frac{m}{v}$

The mass of the liquid is 12.7 grams.

We know that 15 mL of this liquid was added to a 50 mL graduated cylinder. Therefore, the volume is 15 mL. The 50 mL is not relevant, it only tells us about the graduated cylinder.

$m= 12.7 \ g\\v= 15 \ mL$

Substitute the values into the formula.

$d=\frac{12.7 \ g}{ 15 mL}$

Divide.

$d=0.846666667 \ g/mL$

Round to the nearest hundredth. The 6 in the tenth place tells us to round the 4 to a 5.

$d \approx 0.85 \ g/mL$

The density of the liquid is about 0.85 grams per milliliter and choice A is correct.

4 0

3 years ago

The majority of the elements essential to life are found in what part of the periodic table?

IRINA_888 [86]

The rows in the top third - This group consists of elements like Sodium, Magnesium, Potassium and Calcium on the right and Chlorine, Carbon, Nitrogen and Oxygen on the left.
Sodium and Chlorine are components of salt, a very important compound of our blood, essential for transferring electrical signals from the brain to the rest of the body and vice versa. Calcium is the building block of our bones, while Magnesium and potassium ensure proper functioning of our organs.

3 0

3 years ago

The temperature in Jersey City, NJ in mid-Spring is 60*F. The temperature in Miami, FL is 90*F on the same day. Miami is about 1

timurjin [86]

Answer:

Temperature gradient = 30

90F - 60F = 30F

The temperature gradient is 30F.

If I am right, let me know.

7 0

3 years ago

Read 2 more answers

Help! Please :) Thank you

BartSMP [9]

First one??

I believe this is the correct answer

5 0

3 years ago

Calculate the acid dissociation constant of a weak monoprotic acid if a 0.5M solution of this acid gives a hydrogen-ion concentr

RUDIKE [14]

Let the acid be HA.
The chemical formula for this acid will be the following:

$HA \rightleftharpoons H^{+}+A^{-}$

The formula for the acid dissociation constant will be the following:

 $K_a= \dfrac{[H^+][A^-]}{[HA]}$

We know [H+]=0.0001 (it's given).
However, we must find [A-] and [HA] in order to solve for the constant.

We find that [A-]=[H+] by using a electroneutrality equation.
Also, we can create a concentration equation to find [HA].

 $0.5M=[A^-]+[HA]$
$[HA]=0.5M-[A^-]$

Now, we can find the acid dissociation constant.

 $K_a= \dfrac{[H^+][A^-]}{0.5M-[A^-]}$

$= \dfrac{0.0001*0.0001}{0.5-0.0001} = 2.0*10^{-8}$

4 0

3 years ago