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3 years ago

How many grams do 4.8 x 1026 atoms of silicon weigh? Answer in units of g.

1 answer:

7 0

Take the atomic mass of silicon and put it over one. Then set that equal to x over 4.8 x 1026. X will equal to the weight of silicon in grams.

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Which of the following statements is true when considering temperature during a recrystallization? More than one answer may be c

Otrada [13]

Answer:

The correct answer is:

<em>(1) It is important that the sample is dissolved in just enough hot solvent. </em>

Explanation:

The process of recrystallization is important to eliminate the impurities and to obtain better crystals of the solid. The solvent used to perform the recrystallization must have a high dissolution power of the substance to be recrystallized and a low dissolution power of the impurities. This is in order to eliminate most impurities. Furthermore, <em>It is important that the sample is dissolved in just enough hot solvent </em>because this should be easy to remove after the recrystallization and the crystal should form easily when the solution cools. Also, it is better to add the hot solvent to solubilize the crystals and keep the impurities insoluble, instead of adding the cold solvent and heating the solution. Additionally, the process of cooling the solution must be done slowly to obtain large and fewer crystals. A fast ice-cooling will form smaller crystals.

4 0

3 years ago

People take antacids, such as milk of magnesia, to reduce the discomfort of acid stomach or heartburn. The recommended dose of m

Llana [10]

Answer:

$V_{HCl}=0.208L=208mL$

Explanation:

Hello,

In this case, since the chemical reaction is:

$2HCl+Mg(OH)_2\rightarrow MgCl_2+2H_2O$

We can see that hydrochloric acid and magnesium hydroxide are in a 2:1 mole ratio, which means that the neutralization point, we can write:

$n_{HCl}=2*n_{Mg(OH)_2}$

In such a way, the moles of magnesium hydroxide (molar mass 58.3 g/mol) in 500 mg are:

$n_{Mg(OH)_2}=500mg*\frac{1g}{1000mg}*\frac{1mol}{58.3g} =0.00858mol$

Next, since the pH of hydrochloric acid is 1.25, the concentration of H⁺ as well as the acid (strong acid) is:

$[H^+]=[HCl]=10^{-pH}=10^{-1.25}=0.0562M$

Then, since the concentration and the volume define the moles, we can write:

$[HCl]*V_{HCl}=2*n_{Mg(OH)_2}$

Therefore, the neutralized volume turns out:

$V_{HCl}=\frac{2*0.00858mol}{0.0562\frac{mol}{L} }\\ \\V_{HCl}=0.208L=208mL$

Best regards.

3 0

2 years ago

Which of the following questions can be answered by science? (2 points) What makes a song sound beautiful? What is the meaning o

34kurt

Answer:

Explanation:

Its the only answer that actually makes sense and i got it right on the quiz.

5 0

3 years ago

What subatomic particle is most involved in making chemical bonds?

frozen [14]

An electron i hope this helps

5 0

3 years ago

A 4-g mass of NaOH is dissolved in 5mL of water.

lapo4ka [179]

Molar mass NaOH = 40.0 g/mol

Volume in liters of solution :

5 mL / 1000 => 0.005 L

number of moles :

4 / 40 => 0.1 moles

M = n / V

M = 0.1 / 0.005

= 20 mol/L or 20 M

hope this helps!

6 0

2 years ago