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3 years ago

A metal sample has a mass of 64.2 g. What is the density of this metal?

Chemistry

1 answer:

brilliants [131]3 years ago

8 0

density= mass/volume

we need the volume of the metal to find the density, in which case the answer would be 64.2/volume=density

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C) stores heredity information

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Question 12 (4 points)

kozerog [31]

Answer:

100grams

Explanation:

law of conservation of mass

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Consider the reaction. 2 HBr(g) ¡ H2(g) + Br2(g) a. Express the rate of the reaction in terms of the change in concentration of

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Answer :

(A) The rate expression will be:

$Rate=-\frac{1}{2}\frac{d[HBr]}{dt}=+\frac{d[H_2]}{dt}=+\frac{d[Br_2]}{dt}$

(B) The average rate of the reaction during this time interval is, 0.00176 M/s

(C) The amount of Br₂ (in moles) formed is, 0.0396 mol

Explanation :

Rate of reaction : It is defined as the change in the concentration of any one of the reactants or products per unit time.

The given rate of reaction is,

$2HBr(g)\rightarrow H_2(g)+Br_2(g)$

The expression for rate of reaction :

$\text{Rate of disappearance of }HBr=-\frac{1}{2}\frac{d[HBr]}{dt}$

$\text{Rate of disappearance of }H_2=+\frac{d[H_2]}{dt}$

$\text{Rate of formation of }Br_2=+\frac{d[Br_2]}{dt}$

Part A:

The rate expression will be:

$Rate=-\frac{1}{2}\frac{d[HBr]}{dt}=+\frac{d[H_2]}{dt}=+\frac{d[Br_2]}{dt}$

Part B:

$\text{Average rate}=-\frac{1}{2}\frac{d[HBr]}{dt}$

$\text{Average rate}=-\frac{1}{2}\frac{(0.512-0.600)M}{(25.0-0.0)s}$

$\text{Average rate}=0.00176M/s$

The average rate of the reaction during this time interval is, 0.00176 M/s

Part C:

As we are given that the volume of the reaction vessel is 1.50 L.

$\frac{d[Br_2]}{dt}=0.00176M/s$

$\frac{d[Br_2]}{15.0s}=0.00176M/s$

$[Br_2]=0.00176M/s\times 15.0s$

$[Br_2]=0.0264M$

Now we have to determine the amount of Br₂ (in moles).

$\text{Moles of }Br_2=\text{Concentration of }Br_2\times \text{Volume of solution}$

$\text{Moles of }Br_2=0.0264M\times 1.50L$

$\text{Moles of }Br_2=0.0396mol$

The amount of Br₂ (in moles) formed is, 0.0396 mol

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3 years ago

Define metallic bonds

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A metallic bond is a force that holds atoms together in a metallic substance.

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A sample of monochloro pentaborane (9), b5h8cl, has a mass of 20.1 g. what amount, in moles, does this mass represent?

dolphi86 [110]

The number of moles in monochloro pentaborane (9) $B_5H_8Cl$ is 0.37056.

We know that ,

Number of moles = Given mass/ Molar mass

Given mass of monochloro pentaborane (9) is 20.1 g

The molar mass of monochloro pentaborane (9) is

= $5*B + 8*H + Cl$

= $5* 10.811 + 8 * 1 + 35.453$

= 54.241

Thus number of moles = 20.1/54.241

= 0.37056

To know more about mole concept

brainly.com/question/20483253

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2 years ago