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kati45 [8]
2 years ago
7

The titration of a 25.00 mL sample of NaOH required 28.25 mL of a 0.200 M HCl solution to reach the end point. What was the mola

r concentration of the sodium hydroxide solution?
Chemistry
1 answer:
Ksju [112]2 years ago
5 0

Answer:

Mb = 0.226 M

Explanation:

This is a acid base titration between a strong acid and a strong base, therefore, this reactions is completely done, and the reaction is the following:

NaOH + HCl -------> NaCl + H2O

We have here a 1:1 mole ratio, this means that:

1 mole NaOH = 1 mole HCl

Expressing in concentration and volume:

Mb * Vb = Ma * Va

We have concentration and volume of the acid, and the volume of the base, so we can solve for the concentration:

Mb = Ma * Va / Vb

Mb = 28.25 * 0.2 / 25

Mb = 0.226 M

This is the concentration of the NaOH solution

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Decide whether the property measured was a chemical or physical property of X, if you can. If you don’t have enough information
olga nikolaevna [1]

Answer:

<u><em>See attachment for explanations.</em></u>

Explanation:

3 0
1 year ago
What is the best definition for the atomic number in an element
arlik [135]
The atomic number in an element is usually how many protons the element has. For example, Hydrogen has a 1 on top of the H (on the periodic table), therefore, Hydrogen has 1 proton. Oxygen has an 8 on top of the O (on the periodic table) so therefore, Oxygen has 8 protons.
7 0
3 years ago
in order to find the molar mass of an unknown compound, a research scientist prepared a solution of 0.930 g of an unknown in 125
PtichkaEL [24]

Answer:

Molar mass→ 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol

Explanation:

Let's apply the formula for freezing point depression:

ΔT = Kf . m

ΔT = 74.2°C - 73.4°C → 0.8°C

Difference between the freezing T° of pure solvent and freezing T° of solution

Kf = Cryoscopic constant → 5.5°C/m

So, if we replace in the formula

ΔT = Kf . m → ΔT / Kf = m

0.8°C / 5.5 m/°C = m → 0.0516 mol/kg

These are the moles in 1 kg of solvent so let's find out the moles in our mass of solvent which is 0.125 kg

0.0516 mol/kg . 0.125 kg = 6.45×10⁻³ moles. Now we can determine the molar mass:

Molar mass (mol/kg) → 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol

3 0
3 years ago
What is the percent composition by mass of oxygen in Ca(NO3)2 (gram-formula= 164 g/mol)?
Neko [114]
To find this, we will use this formula:

Molar mass of element
------------------------------------ x 100
Molar mass of compound

So, first lets calculate the mass of the compound as a whole. We use the atomic masses on the periodic table to determine this.

Ca: 40.078 g/mol
N2 (there is two nitrogens): 28.014 g/mol
O6 (there are six nitrogens: 3 times 2): 95.994 g/mol

When we add all of those numbers up together, we get 164.086. That is the molar mass for the whole compound. However, we are trying to figure out what percent of the compound oxygen makes up. From the molar mass, we know that 95.994 of the 164.086 is oxygen. Lets plug those numbers into our equation!

95.994
-----------
164.086

When we divide those two numbers, we get .585. When we multiply that by 100, we get 58.5.

So, the percent compostition of oxygen in Ca(NO3)2, or, calcium nitrate, is 58.5%.
5 0
3 years ago
Occupational Safety and Health Administration has set the limit on the maximum percentage of carbon dioxide (CO2) in air a worke
Lyrx [107]

Answer:

The minimum rate of fresh air in the room is 176 moles/min

Explanation:

High exposure of CO₂ has health effects as headaches, increased heart rate, elevated blood pressure, coma, asphyxia, convulsions, etc.

0,500 mole% of CO₂ in air means 0,500 moles of CO₂ per 100 moles of air

As the rate of sublimation of CO₂ is 0,880, the minimum rate of fresh air in the room must be:

\frac{0,500 moles CO_{2}}{100 moles Air} = \frac{0,880 moles CO_{2}/min}{X}

X = <em>176 moles of Air/min</em>

<em></em>

I hope it helps!

4 0
3 years ago
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