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3 years ago

A piece of copper has a mass of 660 g. How many atoms does the sample contain?

1 answer:

4 0

The conversions that will be used are:

1 mole of copper / 63.5 grams of copper
6.02 x 10²³ atoms of copper / 1 mole of copper

Multiplying the given mass by these conversions,

660 g * (1 mol Cu / 63.5 g Cu) * (6.02 x 10²³ Cu atoms / 1 mole Cu)

The sample contains 6.25 x 10²⁴ atoms of copper

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Which ancient African Kingdom is located in western Africa?

NISA [10]

Answer:

Ghana Empire is was a kingdom in western Africa.

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2 years ago

Compare and contrast the Bohr model and the electron cloud models of the atom.

bogdanovich [222]

Here we have to compare the Bohr atomic model with electron cloud model.

In the Bohr's atomic model the electrons of an element is assumed to be particle in nature. Which was unable to explain the deBroglie' hypothesis or the uncertainty principle and has certain demerits.

The uncertainty principle reveals the wave nature of the electrons or electron clod model. The Bohr condition of a stable orbits of the electron can nicely be explained by the electron cloud model, the mathematical form of which is λ = nh/mv, where, λ = wavelength, n is the integral number, h = Planck's constant, m = mass of the electron and v = velocity of the electron.

The integral number i.e. n is similar to the mathematical form of Bohr's atomic model, which is mvr = nh/2π. (r = radius of the orbit).

Thus, the electron cloud model is an extension of the Bohr atomic model, which can explain the demerits of the Bohr model. Later it is revealed that the electron have both particle and wave nature. Which is only can explain all the features of the electrons around a nucleus of an element.

5 0

2 years ago

Read 2 more answers

In the laboratory a student uses a "coffee cup" calorimeter to determine the specific heat of a metal. She heats 19.6 grams of z

storchak [24]

Answer:

The specific heat of zinc is 0.375 J/g°C

Explanation:

Step 1: Data given

Mass of zinc = 19.6 grams

Mass of water = 82.9 grams

Initial temperature of zinc T1= 98.37 °C

Initial temperature of water T1= 24.16 °C

Final temperature of water (and zinc) T2 = 25.70 °C

Specific heat of water = 4.184 J/g°C

Step 2: Calculate Specific heat of zinc

Q=m*c*ΔT

Qzinc = -Qwater

m(zinc)*C(zinc)*ΔT(zinc) = -m(water)*C(water)*ΔT(water)

⇒ with mass of water = 82.9 grams

⇒ with C(water) = 4.184 J/g°C

⇒ with ΔT(water) = T2 - T1 = 25.70 - 24.16 = 1.54

⇒ with mass of zinc = 19.6 grams

⇒ with C(zinc) = TO BE DETERMINED

⇒ with ΔT(zinc) = T2 -T1 = 25.70 - 98.37 = -72.67°C

Qzinc = -Qwater

m(zinc)*c(zinc)* ΔT(zinc) = - m(water)*c(water)* ΔT(water)

19.6g* C(zinc) * (-72.67°C) = - 82.9g* 4.184 J/g°C * 1.54 °C

-1424.332*C(zinc) = -534.155

C(zinc) = 0.375 J/g°C

The specific heat of zinc is 0.375 J/g°C

4 0

2 years ago

How many grams are in 0.5 moles C6H12O6? Show work please!

Nitella [24]

Molar mass of C6H12O6 = 6x12 + 12x1 + 6x16 = 180g

SO mass of 1 mole of C6H12O6 = 180g

mass of 0.5 mole of C6H12O6 = 0.5 x180g = 90g

6 0

2 years ago

How many iron atoms are in 0.32 mol of Fe2031? 3.9x 1023 jron atoms O 3.9 iron atoms O 6.02 x 1023 iron atoms 1.9 x 1023 iron at

Gennadij [26K]

Answer: $3.9\times 10^{23}$ iron atoms

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number $6.023\times 10^{23}$ of particles.

$1 molecule of [tex]Fe_2O_3$ contains= 2 atoms of iron

$1 mole of [tex]Fe_2O_3$ contains= $2\times 6.023\times 10^{23}=12.05\times 10^{23}$ atoms of iron

thus 0.32 moles of $Fe_2O_3$ contains= $\frac{12.05\times 10^{23}}{1}\times 0.32=3.9\times 10^{23}$ atoms of iron

Thus the sample would have $3.9\times 10^{23}$ iron atoms.

8 0

3 years ago