Ask question

Ask question

All categories

sertanlavr [38]

1 year ago

5

One of the basic building blocks of matter, which cannot be broken down by chemical means is a(n)______ , of which there are 92

that occur naturally.

1 answer:

Nadusha1986 [10]1 year ago

6 0

One of the basic building blocks of matter, which cannot be broken down by chemical means is an element.

The first chemical element is hydrogen (atomic number is 1) and the last is oganesson (atomic number is 118).

Elements are scheduled in Periodic table, ordered by their atomic number.

Other example, krypton is a chemical element with symbol Kr and atomic number 36.

Krypton has 36 electron and 36. It is noble gas (group 18).

Noble gases are in group 18: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). They have very low chemical reactivity.

More about chemical element: brainly.com/question/28376204

#SPJ4

You might be interested in

14. What volume (mL) of water do I need to add to 425

Reptile [31]

Answer:

212.5 mL

both the original and the diluted solution have 0.765 moles of KCl

Explanation:

c1V1 = c2V2

V2 = c1V1/c2 = (1.8 M×425 mL)/1.2 M = 637.5 mL

(637.5 - 425) mL = 212.5 mL

n = (1.8 mol/L)(0.425 L) = 0.765 moles of KCl

since it's a dilution, the diluted solution has the same number of moles as the original solution, 0.765 moles of KCl

7 0

3 years ago

Protons, neutrons, and electrons.

natima [27]

What are you asking?

8 0

3 years ago

0.250 moles of NaCl is dissolved in 0.850 L of solution. What is the molar concentration?

Nuetrik [128]

Considering the definition of molarity, the molar concentration is 0.294 $\frac{moles}{liter}$ .

Molarity reflects the concentration of a solution indicating the number of moles of solute that are dissolved in a given volume.

The molarity of a solution is calculated by dividing the moles of the solute by the volume of the solution:

$molarity=\frac{amount of moles of solute}{volume}$

Molarity is expressed in units $\frac{moles}{liter}$ .

In this case, you know:

amount of moles of solute= 0.250 moles
volume= 0.850 L

Replacing in the definition of molarity:

$molarity=\frac{0.250 moles}{0.850 L}$

Solving:

molarity= 0.294 $\frac{moles}{liter}$

Finally, the molar concentration is 0.294 $\frac{moles}{liter}$ .

Learn more about molarity with this example: brainly.com/question/15406534?referrer=searchResults

6 0

2 years ago

In their notebook you see that it takes 9 hours for a sixth of a 0.5M solution of BC2 to react. Unfortunately, you have somewher

trasher [3.6K]

Complete Question

The complete question is shown on the first uploaded image

Answer:

The concentration of $BC_2$ that should used originally is $C_Z_o = 0.4492M$

Explanation:

From the question we are told that

The necessary elementary step is

$2BC_2 ----->4C + B_2$

The time taken for sixth of 0.5 M of reactant to react $t = 9 hr$

The time available is $t_a = 3.5 hr$

The desired concentration to remain $C = 0.42M$

Let Z be the reactant , Y be the first product and X the second product

Generally the elementary rate law is mathematically as

$-r_Z = kC_Z^2 = - \frac{d C_Z}{dt}$

Where k is the rate constant , $C_Z$ is the concentration of Z

From the elementary rate law we see that the reaction is second order (This because the concentration of the reactant is raised to power 2 )

For second order reaction

$\frac{1}{C_Z} - \frac{1}{C_Z_o} = kt$

Where $C_Z_o$ is the initial concentration of Z which a value of $C_Z_o = 0.5M$

From the question we are told that it take 9 hours for the concentration of the reactant to become

$C_Z = C_Z_o - \frac{1}{6} C_Z_o$

$C_Z = 0.5 - \frac{0.5}{6}$

$= 0.4167 M$

So

$\frac{1}{0.4167} - \frac{1}{0.50} = 9 k$

$0.400 = 9 k$

=> $k = 0.044\ L/ mol \cdot hr^{-1}$

For $C_Z = 0.42M$

$\frac{1}{0.42} - \frac{1}{C_Z_o} = 3.5 * 0.044$

$2.38 - 0.154 = \frac{1}{C_Z_o}$

$2.226 = \frac{1}{C_Z_o}$

$C_Z_o = \frac{1}{2.226}$

$C_Z_o = 0.4492M$

4 0

3 years ago

A generator does work on an electric heater by forcing an electric current through it. Suppose 1 kJ of work is done on the heate

azamat

Answer:

The change in internal energy of the heater is 0 kJ

Explanation:

∆U = Q - W

Q is quantity of heat transferred = 1 kJ

W is work done on the heater = 1 kJ

Change in internal energy (∆U) = 1 - 1 = 0 kJ

3 0

3 years ago

Read 2 more answers