All categories

3 years ago

A nanotechnology equipment requires 7.40 x 10^18 atoms of potassium. What is the mass of this sample?

Chemistry

1 answer:

abruzzese [7]3 years ago

5 0

Answer:

4.81×10⁻⁴ g K

Explanation:

Convert atoms to moles:

7.40×10¹⁸ atoms K × (1 mol K / 6.02×10²³ atoms) = 1.23×10⁻⁵ mol K

Convert moles to mass:

1.23×10⁻⁵ mol K × (39.1 g K / mol K) = 4.81×10⁻⁴ g K

You might be interested in

What is the composition, in atom percent, of an alloy that contains a) 45.5 lbm of silver, b) 83.7 lbm of gold, and c) 6.3 lbm o

lyudmila [28]

Answer:

$\% atAg=44.6\%\\\% atAu=44.9\%\\\% atCu=10.5\%$

Explanation:

Hello,

In this case, for computing the atom percent, one must obtain the number of atoms of silver, gold and copper as shown below:

$atomsAg=45.5lbm*\frac{453.59g}{1lbm}*\frac{1molAg}{107.87gAg}*\frac{6.022x10^{23}atomsAg}{1molAg}=1.15x10^{26}atomsAg\\atomsAu=83.7lbm*\frac{453.59g}{1lbm}*\frac{1molAu}{196.97gAu}*\frac{6.022x10^{23}atomsAu}{1molAu}=1.16x10^{26}atomsAu\\atomsCu=6.3lbm*\frac{453.59g}{1lbm}*\frac{1molAg}{63.55gCu}*\frac{6.022x10^{23}atomsCu}{1molCu}=2.71x10^{25}atomsCu$

Thus, the atom percent turns out:

$\% atAg=\frac{1.15x10^{26}}{1.15x10^{26}+1.16x10^{26}+2.71x10^{25}}*100\% =44.6\%\\\% atAu=\frac{1.16x10^{26}}{1.15x10^{26}+1.16x10^{26}+2.71x10^{25}}*100\% =44.9\%\\\% atCu=\frac{2.71x10^{25}}{1.15x10^{26}+1.16x10^{26}+2.71x10^{25}}*100\% =10.5\%$

Best regards.

4 0

3 years ago

Answer questions a-c about the Bronsted acid-base reaction below using the identifying letters A-D below each structure. The pKa

GuDViN [60]

Answer:

a H2CO3 b HCO3- and c H+ and HCO3-

Explanation:

As the pKa value of phenol is more than that of carbonic acid(H2CO3), the carbonic acid will have high Ka value than that of phenol.

The acid that contain high Ka value act as stong acid.From that point of view H2CO3 is a strong acid than phenol as the Ka value of carbonic acid is greater than that of phenol.

The conjugate base of H2CO3 is bicarbonate ion(HCO3-)

c The species that predorminates at equilibrium are H+ and HCO3-

8 0

2 years ago

Ne, Ar, and Kr have which properties in common? Group of answer choices

jasenka [17]

Answer:

Ne, Ar, and Kr are gases at STP, unreactive, and are generally monatomic.

Explanation:

they are unreactive and monoatomic and thats why have a very low boiling point.

6 0

3 years ago

Which is a nonpolar molecule?

Nookie1986 [14]

what is a non-polar molecule? Atoms are made of small particles. When atoms bond together to form molecules. They share or give electrons. If the electrons are shared equally by the atoms, then there is no resulting charge making the molecule nonpolar. Polar molecules are the complete opposite.

5 0

2 years ago

Read 2 more answers

Write the formula for potassium oxide. why do you not need prefixes in the name

Molodets [167]

Potassium oxide: K₂O.

There's no need for prefixes since K₂O is an ionic compound.

<h3>Explanation</h3>

Find the two elements on a periodic table:

Potassium- K- on the left end of period four.
Oxygen- O- near the right end of periodic two.

Elements on the bottom-left corner of the periodic table are metals. Those on the top-right corner are nonmetals.

Potassium is a metal,
Oxygen is a nonmetal.

A metal and a nonmetal combine to form an ionic compound. Potassium oxide is likely to be an ionic compound. It contains two types of ions:

Potassium ions: Potassium is group 1 of the periodic table. It is an alkaline metal. Like other alkaline metals such as sodium Na, potassium K tends to lose one electron and form ions of charge +1 in compounds. The ion would be K⁺.

Oxide ions from oxygen: Oxygen is the second most electronegative element on the periodic table. It tends to gain two electrons and form the oxide ion $\text{O}^{2-}$ when it combines with metals.

The two types of ions carry opposite charges. They shall pair up at a certain ratio such that they balance the charge on each other. The charge on each $\text{O}^{2-}$ ion is twice that on a $\text{K}^{+}$ ion. Each $\text{K}^{+}$ would pair up with two $\text{O}^{2-}$ . Hence the subscript in the formula: $\text{K}_{\bf 2}\text{O}$ .

There are two classes of compounds:

Covalent compounds, which need prefixes, and
Ionic compounds, which need no prefix.

Prefixes are needed only in covalent compounds. For instance in the covalent compound carbon dioxide $\text{CO}_2$ , the prefix di- indicates that there are two oxygen atoms in the formula $\text{CO}_2$ . However, there's no need for prefix in ionic compounds such as $\text{K}_2\text{O}$ .

7 0

3 years ago