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2 years ago

If a penny is made of 3.11 grams of copper, how many atoms of copper are in the penny

Chemistry

1 answer:

Pie2 years ago

8 0

Answer:

2.94x10²² atoms of Cu

Explanation:

We must work with NA to solve this, where NA is the number of Avogadro, number of particles of 1 mol of anything.

Molar mass Cu = 63.55 g/mol

Mass / Molar mass = Mol → 3.11 g / 63.55 g/m = 0.0489 moles

1 mol of Cu has 6.02x10²³ atoms of Cu

0.0489 moles of Cu, will have (0.0489 .NA)/ 1 = 2.94x10²² atoms of Cu

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Cylinders of compressed gas are typically filled to a pressure of 200 bar. For oxygen, what would be the molar volume at this pr

mars1129 [50]

Answer:

$V = 0.124 \ Liters$

$V = 0.112 \ Liters$

Explanation:

From the question we are told that

The pressure of compressed gas is $P = 200 \ bar = \frac{200}{1.013}= 197.4 \ atm$

The temperature is $T = 25^oC = 25 + 273 = 298 \ K$

Generally the perfect gas equation is mathematically represented as

$PV = nRT$

substituting 0.08206 L-atm/mol-K for R and 1 mole for n

We have that

$V = \frac{1 * 0.08206 * 298 }{ 197.4}$

$V = 0.124 \ Liters$

Generally the van der Waals equation is mathematically represented as

$nRT = [P + \frac{n^2 * a }{V^2 } ][V - nb]$

=> $1 * 0.08206 *298 = [197.4 + \frac{1^2 * 1.364}{V^2 } ][V - 1 * 3.19 * 10^{-2}]$

=> $V = 0.112 \ Liters$

7 0

2 years ago

What is the mass of an original 5.60-gram sample of iron-53 that remains unchanged after 25.53 minutes? 0.35 g 0.70 g 1.40 g 2.8

djverab [1.8K]

Answer: 0.70g

The half-life of iron-53 would be 8.51 minutes. So, in 25.53 minutes would be equal to: 25.53 min/ (8.51 minutes/ half-life)= 3 half-life.

Every half-life will reduce the original weight into half. So, the final weight would be:
final weight = original weight * 1/2 ^(time)
final weight = 5.6g * (1/2)^(3 half-life)
final weight = 5.6g * 1/8= 0.7g

3 0

2 years ago

A brick has dimensions of 15 cm by 6.0 CM by 12 CM what is the volume of the brick in cubic meters

VLD [36.1K]

The volume of the brick in cubic meters is 0.00108 m³

calculation

volume of a brick =length x width x height

-length = 15 cm

width = 6.0 cm

height = 12 cm

volume is therefore= 15 cm x 6.0 cm x 12 cm =1080 cm³

convert 1080 cm³ into m³

that is 1 cm³ = 1 x 10^-6m³

1080 cm³ = ? m³

by cross multiplication

=[ (1080 cm³ x 1 x10^-6 m³) / 1 cm³] = 0.00108 m³

7 0

1 year ago

If a runner completes a 10 kilometer race in 32.50 minutes, what is the 10.0 km pace in miles per hour? (1.609 km = 1 mile appro

Elina [12.6K]

If a runner completes a 10 km race in 32.5 minutes, his pace or speed can be calculated by the equation:

velocity = distance/time = 10km/32.5 mins = 0.3125 km/min

Convert this value to miles per hour using the conversion factors for minutes to hours and kilometers to miles as requested by the problem. This gives an answer of 11.47 miles per hour.

0.3125 km/min x 60 mins./ 1 hour x 1 mile / 1.609 km = 11.47 miles/hour

3 0

2 years ago

Aqueous magnesium chloride is added to aqueous silver nitrate. A white precipitate forms. Write the chemical equation for this r

Butoxors [25]

Answer:

1. Molecular equation

BaCl2(aq) + 2AgNO3(aq) –> 2AgCl(s) + Ba(NO3)2 (aq)

2. Complete Ionic equation

Ba²⁺(aq) + 2Cl¯(aq) + 2Ag⁺(aq) + 2NO3¯ (aq) —> 2AgCl(s) + Ba²⁺(aq) + 2NO3¯(aq)

3. Net ionic equation

Cl¯(aq) + Ag⁺(aq) —> AgCl(s)

Explanation:

4 0

2 years ago

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