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3 years ago

What is common to all elements in the same group on the periodic table? Their properties are very different.

Chemistry

2 answers:

Mrac [35]3 years ago

7 0

Hello,

B.They have the same number of valence electrons.

sattari [20]3 years ago

7 0

B. They have the same number of valence

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The ka for hcn is 4.9 ⋅ 10-10. What is the value of kb for cn-?

marusya05 [52]

Answer:

kb = 2,0x10⁻⁵

Explanation:

The ka for HCN is:

HCN ⇄ H⁺ + CN⁻; ka = 4,9x10⁻¹⁰ (1)

The inverse reaction has an equilibrium constant of:

H⁺ + CN⁻ ⇄ HCN k = 1/4,9x10⁻¹⁰ = 2,0x10⁹ (2)

As the equilibrium of the water is:

H₂O ⇄ H⁺ + OH⁻; kw = 1x10⁻¹⁴ (3)

The sum of (2) + (3) gives:

H₂O + CN⁻ ⇄ HCN + OH⁻; kb = kw×k = 1x10⁻¹⁴×2,0x10⁹ =

2,0x10⁻⁶; kb = 2,0x10⁻⁵

-In fact, the general formula to convert from ka to kb is:

kb = kw / ka-

I hope it helps!

5 0

3 years ago

Why do weak acid-weak base reactions not go to completion?

vladimir2022 [97]

Neither a weak acid nor a weak base has a strong tendency to transfer H+ ions that is why weak acid-weak base reactions not go to completion.

4 0

3 years ago

Read 2 more answers

It takes 60 mL of 0.20 M of sodium hydroxide (NaOH) to neutralize 25 mL of carbonic acid (H2CO3) for the following chemical reac

irina1246 [14]

If It takes 60mL of 0.20M of sodium hydroxide (NaOH) to neutralize 25 mL of carbonic acid ( $H_2CO_3$ ), then the concentration of the carbonic acid is 0.24M

The reaction between NaOH solution and $H_2CO_3$ is written below

$2NaOH + H_2CO_3 \rightarrow Na_2CO_3 + 2H_2O$

Volume of NaOH, $V_B$ = 60 ml

Volume of $H_2CO_3$ , $V_A=25 ml$

Molarity of $H_2CO_3$ , $C_A=?$

Molarity of NaOH, $C_B=0.20M$

Number of moles of $H_2CO_3$ , $n_A=1$

Number of moles of NaOH, $n_B=2$

The mathematical equation for neutralization reaction is:

$\frac{C_AV_A}{C_BV_B} =\frac{n_A}{n_B}$

Substitute $C_B=0.2 M$ , $n_A=1$ , $n_B=2$ , $V_B$ = 60ml, and $V_A=25 ml$ into the equation above in order to solve for $C_A$

$\frac{C_A \times 25}{0.2 \times 60}=\frac{1}{2} \\\\50C_A=12\\\\C_B=\frac{12}{50} \\\\C_B=0.24M$

Therefore, the concentration of the carbonic acid is 0.24M

Learn more here: brainly.com/question/25943090

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2 years ago

In the iodoform test why is it necessary to add sodium hypochlorite

Kobotan [32]

Sodium hypochlorite is used in iodoform test for the oxidation of alcohol to aldehyde as shown in the image attached:

Here sodium hypochlorite is formed by the reaction of NaOH with I2 that further oxides alcohols to aldehydes.

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2 years ago

Geologists use the Law of Superposition to date rock layers. However, the Earth's

Allisa [31]

The answer is d faults

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2 years ago