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3 years ago

Which of the following statements is true?

Chemistry

1 answer:

VLD [36.1K]3 years ago

5 0

Answer:

C is correct

Explanation:

For example, you move your hands together you are creating friction.

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Based on the location of nitrogen on the periodic table how many additional electrons does a nitrogen atom need in its valence s

igor_vitrenko [27]

1 additional electron

5 0

3 years ago

A 0.25-mol sample of a weak acid with an unknown Pka was combined with 10.0-mL of 3.00 M KOH, and the resulting solution was dil

Masteriza [31]

Answer : The value of $pK_a$ of the weak acid is, 4.72

Explanation :

First we have to calculate the moles of KOH.

$\text{Moles of }KOH=\text{Concentration of }KOH\times \text{Volume of solution}$

$\text{Moles of }KOH=3.00M\times 10.0mL=30mmol=0.03mol$

Now we have to calculate the value of $pK_a$ of the weak acid.

The equilibrium chemical reaction is:

$HA+KOH\rightleftharpoons HK+H_2O$

Initial moles 0.25 0.03 0

At eqm. (0.25-0.03) 0.03 0.03

= 0.22

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

$pH=pK_a+\log \frac{[HK]}{[HA]}$

Now put all the given values in this expression, we get:

$3.85=pK_a+\log (\frac{0.03}{0.22})$

$pK_a=4.72$

Therefore, the value of $pK_a$ of the weak acid is, 4.72

7 0

3 years ago

How many milligrams of AgNO3 is required to completely react with 81.5 mg LiOH?

BartSMP [9]

Answer:

$m_{AgNO_3}=577.6mg$

Explanation:

Hello there!

In this case, according to the given chemical reaction, it is first necessary to compute the moles of reacting LiOH given its molar mass:

$n_{LiOH}=81.5mg*\frac{1g}{1000mg}*\frac{1mol}{23.95g} =0.0034molLiOH$

Thus, since there is a 1:1 mole ratio between lithium hydroxide and silver nitrate (169.87 g/mol) the resulting milligrams turn out to be:

$m_{ AgNO_3}=0.0034molLiOH*\frac{1molAgNO_3}{1molLiOH} *\frac{169.87gAgNO_3}{1molAgNO_3} *\frac{1000gAgNO_3}{1gAgNO_3} \\\\m_{AgNO_3}=577.6mg$

Best regards!

7 0

2 years ago

Question 4 options: _____________ use an element's symbol and show valence electrons

Natali [406]

AnswerLewis symbols are diagrams that show the number of valence electrons of a particular ... of the elements with their number of valence electrons represented as dots ... Only the electrons in the valence level are shown using this notation.:

yaaa

Explanation:

4 0

3 years ago

at what temperature will a fixed amount of gas with a volume of 175 L at 15 degrees celsius and 760mmHg occupy a volume of 198L

Jlenok [28]

Answer: The temperature when the volume and pressure has changed is 274 K

Explanation:

To calculate the pressure when temperature and volume has changed, we use the equation given by combined gas law. The equation follows:

$\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}$

where,

$P_1,V_1\text{ and }T_1$ are the initial pressure, volume and temperature of the gas

$P_2,V_2\text{ and }T_2$ are the final pressure, volume and temperature of the gas

We are given:

$P_1=760mmHg\\V_1=175L\\T_1=15^oC=[15+273]K=288K\\P_2=640mmHg\\V_2=198L\\T_2=?K$

Putting values in above equation, we get:

$\frac{760mmHg\times 175L}{288K}=\frac{640mmHg\times 198L}{T_2}\\\\T_2=274K$

Hence, the temperature when the volume and pressure has changed is 274 K

8 0

3 years ago

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