What volume of 5 M NaOH is needed to create a 100 mL solution of 1 M NaOH?

What are the best note taking styles for high school?

photoshop1234 [79]

Answer:

cornell noted

Explanation:

used in middle school and can be helpful for subjects like ela history and science

5 0

3 years ago

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Please help with this chemistry question it’s due by midnight

Scilla [17]

Answer:

HF is the limiting reactant

Explanation:

The balanced equation for the reaction is given below:

SiO₂ + 4HF —> SiF₄ + 2H₂O

From the balanced equation above,

1 mole of SiO₂ reacted with 4 moles of HF.

Finally, we shall determine the limiting reactant. This can be obtained as illustrated below:

From the balanced equation above,

1 mole of SiO₂ reacted with 4 moles of HF.

Therefore, 7.5 moles of SiO₂ will react with = 7.5 × 4 = 30 moles of HF.

From the calculation made above, we can see clearly that it will take a higher amount (i.e 30 moles) of HF than what was given from the question (i.e 5 moles) to react completely with 7.5 moles of SiO₂.

Therefore, HF is the limiting reactant and SiO₂ is the excess reactant.

3 0

3 years ago

If 50.0 g of formic acid (hcho2, ka = 1.8 x 10^-4) and 30.0 g of sodium formate (NaCHO2) are dissolved to make 500 ml. of soluti

gizmo_the_mogwai [7]

If 50.0 g of formic acid (HCHO2, ka = 1.8 x 10^-4) and 30.0 g of sodium formate (NaCHO2) are dissolved to make 500 ml. of solution, the ph of this solution is 3.35.

Therefore, option C is the correct option.

Given,

Given mass of sodium formate = 30 g

Given mass of formic acid = 50 g

Volume of sodium formate = 500 ml

Volume of formic acid = 500ml

Molar mass of sodium formate = 68 g

Molar mass of formic acid = 46 g

<h3>To calculate concentration of sodium formate and formic acid</h3>

The ratio of number of moles and the volume of solution is Molar concentration of substance.

Concentration of sodium formate

Cb = 30/(68×500)

= 0.00088m

Concentration of formic acid

Ca = 50/(46×500)

= 0.00217m

Now,

by using Henderson hesselbalch equation,

pH = pKa + log(Cb/Ca)

pKa = -log(1.8 × 10^(-4))

= 3.75

pH = 3.75 + log(0.00088/0.00217)

pH = 3.75 - 0.392

pH = 3.35

Thus, we calculated that the value of pH of solution of formic acid and sodium formate is 3.35.

learn more about pH:

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3 0

2 years ago

Which of the following is a heterogeneous mixture

marishachu [46]

Heterogeneous Mixtures aren't uniform and are separated in the mixture. They are usually more easily able to be separated. An example is milk and cereal. The cereal isn't uniform because the milk and cereal still are separated and have their own identities. (You can easily just remove cereal from milk using a strainer)

Homogeneous Mixtures are uniform in composition and the multiple elements have become one solution. These mixtures are hard to separate into their components. An example is tap water because it contains water as well as various minerals that can only be separated by performing chemical reactions.

3 0

3 years ago

A Se ion has a mass number of 79 and a charge of − 2 . Determine the number of neutrons, protons, and electrons in this ion.

posledela

Answer:

45, 34, 36

Explanation:

The atomic number of Selenium is 34 and the atomic number is 79 also the atom has gained two electron denoted by superscript -2

number of neutrons = mass number - atomic number = 79 - 34 = 45

number of proton = atomic number = 34

number of electron = 34 + 2 = 36. In an atom the number of proton is always equal to number of electron if the atom is neutral but this Se atom has gain two so the number of electron will exceed the number of proton by 2.

8 0

3 years ago