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3 years ago

When adding the measurements 42.1014 g + 190.5 g, the answer has ___ significant figures.

Chemistry

1 answer:

andrezito [222]3 years ago

4 0

Answer: The answer has 7 significant figures

Explanation:

The addition of 190.5 and 42.1014 will give 232.6014. Counting the digits will give 7 significant figures.

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Hamid made this table to organize his notes on the properties of acids and bases.

Molodets [167]

Answer : The property in the wrong column is, base form hydrogen gas with metals

Explanation :

Acid : It is a substance that has ability of donating a proton or hydrogen ion, $H^+$ .

The properties of an acid are :

Acids are sour in taste.
It conduct electricity.
The texture of an acid solution is sticky.
It react with carbonates to give salt.
It changes the color of the litmus paper to red.
It react with a metal to give compound and hydrogen gas.

Base : It is a substance that has ability of donating hydroxide ion, $OH^-$ .

The properties of an base are :

Base are bitter in taste.
It conduct electricity.
The texture of an base solution is slippery.
It changes the color of the litmus paper to blue.
It does not react with a metal.

Hence, from the above information, we conclude that the property in the wrong column is, base form hydrogen gas with metals .

8 0

3 years ago

Read 2 more answers

A buffer solution contains 0.306 M C6H5NH3Br and 0.418 M C6H5NH2 (aniline). Determine the pH change when 0.124 mol HCl is added

Ulleksa [173]

Answer: The pH change of the buffer is 0.30

Explanation:

To calculate the pH of basic buffer, we use the equation given by Henderson Hasselbalch:

$pOH=pK_b+\log(\frac{[\text{conjugate acid}]}{[\text{base}]})$

$pOH=pK_b+\log(\frac{[C_6H_5NH_3^+]}{[C_6H_5NH_2]})$ .....(1)

We are given:

$pK_b$ = negative logarithm of base dissociation constant of aniline = 9.13

$[C_6H_5NH_3^+]=0.306M$

$[C_6H_5NH_2]=0.418M$

pOH = ?

Putting values in equation 1, we get:

$pOH=9.13+\log(\frac{0.306}{0.418})\\\\pOH=8.99$

To calculate pH of the solution, we use the equation:

$pH+pOH=14\\pH_{initial}=14-8.99=5.01$

To calculate the molarity, we use the equation:

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

Moles hydrochloric acid solution = 0.124 mol

Volume of solution = 1 L

Putting values in above equation, we get:

$\text{Molarity of HCl}=\frac{0.124}{1L}\\\\\text{Molarity of HCl}=0.124M$

The chemical reaction for aniline and HCl follows the equation:

$C_6H_5NH_2+HCl\rightarrow C_6H_5NH_3^++Cl^-$

Initial: 0.418 0.124 0.306

Final: 0.294 - 0.430

Calculating the pOH by using using equation 1:

$pK_b$ = negative logarithm of base dissociation constant of aniline = 9.13

$[C_6H_5NH_3^+]=0.430M$

$[C_6H_5NH_2]=0.294M$

pOH = ?

Putting values in equation 1, we get:

$pOH=9.13+\log(\frac{0.430}{0.294})\\\\pOH=9.29$

To calculate pH of the solution, we use the equation:

$pH+pOH=14\\pH_{final}=14-9.29=4.71$

Calculating the pH change of the solution:

$\Delta pH=pH_{initial}-pH_{final}\\\\\Delta pH=5.01-4.71=0.30$

Hence, the pH change of the buffer is 0.30

8 0

3 years ago

Which statement is true of the following reaction? H2 + O2 -> 2H+ O2-

Ede4ka [16]

B.it is not balanced for charge or for number of atoms.

6 0

3 years ago

Which substance do plants use to capture light energy from the sun? a) Carbon dioxide b) Chlorophyll c) Glucose d) Oxygen

Akimi4 [234]

Answer: chlorophyll

Explanation:

The substance that plants use to capture light energy from the sun is referred to as chlorophyll.

The chlorophyll is a colored pigment that is used by the plants for photosynthesis. The function of the chlorophyll is that it absorbs the energy from the sun which is then turned into a chemical energy.

6 0

3 years ago

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In which shell are the valence electrons of the elements in Period 2 found?

defon

B 2
is which shell are the valence electrons of the elements in period 2 found

8 0

3 years ago

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