This question is very hard and I'm having trouble with it

A certain radioactive element has a half-life of one hour. If you start with 40.0 grams of the element at noon, how much of the

Tpy6a [65]

If you start with 40.0 grams of the element at noon, 10.0 grams radioactive element will be left at 2 p.m. The correct answer between all the choices given is the second choice or letter B. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.

5 0

3 years ago

Read 2 more answers

If you assume this reaction is driven to completion because of the large excess of one ion, what is the concentration of [Fe(SCN

viktelen [127]

Answer : The concentration of $[Fe(SCN)]^{2+}$ is, $4.32\times 10^{-4}M$

Explanation :

When we assume this reaction is driven to completion because of the large excess of one ion then we are assuming limiting reagent is $SCN^-$ and $Fe^{3+}$ is excess reagent.

First we have to calculate the moles of KSCN.

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

$\text{Moles of }KSCN=0.00180M\times 0.006L=1.08\times 10^{-5}mol$

Moles of KSCN = Moles of $K^+$ = Moles of $SCN^-$ = $1.08\times 10^{-5}mol$

Now we have to calculate the concentration of $[Fe(SCN)]^{2+}$

$\text{Concentration of }[Fe(SCN)]^{2+}=\frac{\text{Moles of }[Fe(SCN)]^{2+}}{\text{Volume of solution}}$

Total volume of solution = (6.00 + 5.00 + 14.00) = 25.00 mL = 0.025 L

$\text{Concentration of }[Fe(SCN)]^{2+}=\frac{1.08\times 10^{-5}mol}{0.025L}=4.32\times 10^{-4}M$

Thus, the concentration of $[Fe(SCN)]^{2+}$ is, $4.32\times 10^{-4}M$

7 0

3 years ago

The switch is used to ___________ or __________ an electrical circuit. When the switch is on, the circuit is __________ , and wh

Pani-rosa [81]

Answer:

The switch is used to disconnect or connect an electrical circuit. When the switch is on, the circuit is complete, and when the switch is off, the circuit is open. Electrical current exists in the circuit when it is closed, but when it is open, there is no electrical current in the circuit. The switch determines whether the circuit is open and closed.

6 0

3 years ago

What molarity of nitric acid (HNO3) was used if 2.00 L must be used to prepare 4.5 L of a 0.25 M HNO3 solution?

Ymorist [56]

The molarity of (HNO₃) that was used if 2.00 L must be used to prepare 4.5 L of a 0.25M HNO₃ solution is 0.563 M

calculation

This is calculated usind M₁V₁=M₂V₂ formula

where,

M₁( molarity ₁) = ?

V₁( volume ₁) = 2.00 L

M₁ (molarity ₂) = 0.25M

V₂( volume₂) = 4.5 L

make M₁ the subject of the formula by diving both side of the formula by V₁

M₁ is therefore = M₂V₂/V₁

M₁ =[ (0.25 M x 4.5 L) / 2.00 L ] =0.563 M

5 0

3 years ago

For the chemical reaction

polet [3.4K]

Answer:

806.3g

Explanation:

Given parameters:

Number of moles of silver nitrate = 4.85mol

Unknown:

Mass of silver chromate = ?

Solution:

2AgNO₃ + Na₂CrO₄ → Ag₂CrO₄ + 2NaNO₃

To solve this problem, we work from the known to the unknown;

The known specie here is AgNO₃ ;

From the balanced chemical equation;

2 moles of AgNO₃ will produce 1 mole of Ag₂CrO₄

4.85 moles of AgNO₃ will produce $\frac{4.85}{2}$ = 2.43moles of Ag₂CrO₄

Mass of silver chromate produced;

mass = number of moles x molar mass

Molar mass of Ag₂CrO₄

Atomic mass of Ag = 107.9g/mol

Cr = 52g/mol

O = 16g/mol

Input the parameters and solve;

Molar mass = 2(107.9) + 52 + 4(16) = 331.8g/mol

So,

Mass of Ag₂CrO₄ = 2.43 x 331.8 = 806.3g

8 0

3 years ago

This question is very hard and I'm having trouble with it​

This question is very hard and I'm having trouble with it