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4 years ago

Why must contact lenses be removed before you enter a chemistry laboratory?

1 answer:

6 0

The vapors of some chemicals used in the chemistry laboratory, especially isocyanates, can react and bond the contact lens to the eye.

(FYI - the family of isocyanates include Superglue..I wouldn't want to have been the person who discovered this unfortunate reaction!)

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Consider Example 12.10. Suppose the experiment is repeated with 0.032 mol of helium instead with everything else staying the sam

Lemur [1.5K]

Answer:

120 extracted from the gas

Explanation:

5 0

3 years ago

In this experiment we will be using a 0.05 M solution of HCl to determine the concentration of hydroxide (OH-) in a saturated so

gulaghasi [49]

<u>Answer:</u> The moles of hydroxide ions present in the sample is 0.0008 moles

<u>Explanation:</u>

To calculate the concentration of acid, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is HCl.

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is $Ca(OH)_2$

We are given:

$n_1=1\\M_1=0.05M\\V_1=16mL\\n_2=2\\M_2=?M\\V_2=36.0mL$

Putting values in above equation, we get:

$1\times 0.05\times 16=2\times M_2\times 36\\\\M_2=\frac{1\times 0.05\times 16}{2\times 36}=0.011M$

To calculate the moles of hydroxide ions, we use the equation used to calculate the molarity of solution:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (in mL)}}$

Molarity of solution = 0.011 M

Volume of solution = 36.0 mL

Putting values in above equation, we get:

$0.011=\frac{\text{Moles of }Ca(OH)_2\times 1000}{36}\\\\\text{Moles of }Ca(OH)_2=\frac{0.011\times 36}{1000}=0.0004mol$

1 mole of calcium hydroxide produces 1 mole of calcium ions and 2 moles of hydroxide ions.

Moles of hydroxide ions = (0.0004 × 2) = 0.0008 moles

Hence, the moles of hydroxide ions present in the sample is 0.0008 moles

8 0

3 years ago

What is the symbol for the carbon isotope with seven neutrons?

Tresset [83]

Carbon -13 has 7 neutrons and carbon -12 has six neutrons. Carbon -12 is the most common isotope of Carbon. Carbon -14 is radioactive and vary rare. The symbols for the isotopes of Carbon atoms shown here indicate they each have six protons but mass numbers of 14, 13, and 12. Hope this helps. :)

8 0

3 years ago

What can you summarize about the use of acid-base indicators?

densk [106]

An acid-base indicator is used to identify the presence of an acid or base. These indicators exhibit different colors depending on the solution that they are in. They are especially useful when completing titrations to determine the molarity of an unknown substance and is denoted as option D.

<h3>What is Titration?</h3>

This is done in the laboratory and involves the slow addition of one solution of a known concentration to a known volume of another solution of unknown concentration.

Acid-base indicators are used to determine the presence of an acid or base in a solution which is based on the colors seen when performing the chemical reaction.

It is used to calculate the the molarity of an unknown substance through the knowledge of the other parameters which is therefore the reason why option D was chosen as the most appropriate choice.

Read more Acid-base indicators here brainly.com/question/2815636

#SPJ1

6 0

1 year ago

A beam of light has a wavelength of 24.0 μm ( μm = 10 -6m). What is its frequency?

vfiekz [6]

Answer:

Frequency = 1.25 ×10¹³ Hz

Explanation:

Given data:

Wavelength of light = 24.0 μm (2.4 ×10⁻⁵ m)

Frequency = ?

Solution:

Formula:

Speed of light = wavelength × frequency

Speed of light /wavelength = frequency

Frequency = 3×10⁸ m /s /2.4 ×10⁻⁵m

Frequency = 1.25 ×10¹³ s⁻¹

s⁻¹ = Hz

Frequency = 1.25 ×10¹³ Hz

6 0

3 years ago