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2 years ago

What is the mass of 4.84×10^21 platinum atoms?

Chemistry

2 answers:

AlekseyPX2 years ago

8 0

Answer:

$\boxed {\boxed {\sf 1.57 \ g \ Pt}}$

Explanation:

We are asked to find the mass of 4.84 × 10²¹ platinum (Pt) atoms.

<h3>1. Atoms to Moles </h3>

First, we convert atoms to moles using Avogadro's Number of 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance. In this case, the particles are platinum atoms. There are <u>6.022 × 10²³ platinum atoms in 1 mole of platinum. </u>

We will convert using dimensional analysis, so we set up a ratio using the underlined information.

$\frac {6.022 \times 10^{23} \ atoms \ Pt }{ 1 \ mol \ Pt}$

We are converting 4.84 × 10²¹ platinum atoms to moles, so we multiply the ratio by this value.

$4.84 \times 10^{21} \ atoms \ Pt *\frac {6.022 \times 10^{23} \ atoms \ Pt }{ 1 \ mol \ Pt}$

Flip the ratio so the units of atoms of platinum cancel.

$4.84 \times 10^{21} \ atoms \ Pt *\frac{ 1 \ mol \ Pt} {6.022 \times 10^{23} \ atoms \ Pt }$

$4.84 \times 10^{21} *\frac{ 1 \ mol \ Pt} {6.022 \times 10^{23} }$

$\frac{4.84 \times 10^{21} } {6.022 \times 10^{23} } \ mol \ Pt$

$0.008037196945 \ mol \ Pt$

<h3>2. Moles to Grams </h3>

Next, we convert moles to grams using the molar mass. This is the mass of 1 mole of a substance. It is found on the Periodic Table because it is equal to the atomic mass, but the units are grams per mole instead of atomic mass units.

Look up the molar mass of platinum.

Pt: 195.08 g/mol

Set up another ratio using the molar mass.

$\frac {195.08 \ g \ Pt}{ 1 \ mol \ Pt}$

We multiply the ratio by the number of moles we calculated.

$0.008037196945 \ mol \ Pt * \frac{195.08 \ g \ Pt}{ 1 \ mol \ Pt}$

The units of moles of platinum cancel.

$0.008037196945 * \frac{195.08 \ g \ Pt}{ 1 }$

$0.008037196945 * {195.08 \ g \ Pt}$

$1.56789638 \ g \ Pt$

<h3>3. Round </h3>

The original value of atoms has 3 significant figures, so our answer must have the same. For the number we found, that is the hundredth place. The 7 in the thousandth place tells us to round the 6 up to a 7.

$1.57 \ g \ Pt$

4.84 × 10²¹ platinum atoms have a mass of <u>1.57 grams.</u>

Ket [755]2 years ago

7 0

The mass will be 1.54g

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A student has a 2.19 L bottle that contains a mixture of O 2 , N 2 , and CO 2 with a total pressure of 5.57 bar at 298 K . She k

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<u>Answer:</u> The partial pressure of oxygen gas is 2.76 bar

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P = pressure of the gas = 5.57 bar

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T = Temperature of the gas = 298 K

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n = Total number of moles = ?

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To calculate the mole fraction of carbon dioxide, we use the equation given by Raoult's law, which is:

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$\chi_A$ = mole fraction of carbon dioxide = ?

Putting values in above equation, we get:

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4 years ago

Joan’s initial nickel (II) chloride sample was green and weighed 4.3872 g. After the dehydration reaction and removal of excess

ANEK [815]

Answer:

a) yes, it was an hydrate

b) the number of waters of hydration, x = 6

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a) yes it was an hydrate because the mass decreased after the process of dehydration which means removal of water thus some water molecules were present in the sample.

b) NiCl2. xH2O

mass if dehydrated NiCl2 = 2.3921 grams

mass of water in the hydrated sample = mass of hydrated - mass of dehydrated = 4.3872 - 2.3921 = 1.9951 g which represent the mass of water that was present in the hydrated sample.

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mole of water = m/Mm = 1.9951/18.02 = 0.11072 mole

Divide both by the smallest number of mole (which is for NiCl2) to find the coefficient of each

for NiCl2 = 0.01846/0.01846 = 1

for H2O = 0.11072/0.01846 = 5.9976 = 6

thus the hydrated sample was NiCl2. 6H2O

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