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Phantasy [73]
3 years ago
14

3. Calculate the number of nickel atoms in a 5-cent coin of mass 0.942g if it was made of an alloy consisting of 75% copper and

25% nickel
Chemistry
1 answer:
arlik [135]3 years ago
3 0

Answer:

2.41x10²¹ atoms

Explanation:

mass of nickel that are present in the coin can be determined Using ( 25% nickel) with j mass of coin= 0.942g )

mass of nickel = (0.942g) × (25/100)

= 0.2355g of Nickel

We need to convert this " gram" into " moles"

Mole= mass/ molar mass

Molar mass= 58.69 g/mol

0.2355 g) / (58.69 g/mol)

= 0.004 mol

We need to convert the moles to

number of atoms.

Avogadro's number= 6.023x10²³ atoms/mol

(0.004 × 6.023x10²³ atoms/mol)

=2.41x10²¹ atoms

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What is the new volume of a 61 L sample at STP that is moved to 183 K and 0.60 atm?
Volgvan

Answer: The new volume of a 61 L sample at STP that is moved to 183 K and 0.60 atm is 54.63 L.

Explanation:

Given: V_{1} = 61 L,      T_{1} = 183 K,      P_{1} = 0.60 atm

At STP, the value of pressure is 1 atm and temperature is 273.15 K.

Now, formula used to calculate the new volume is as follows.

\frac{P_{1}V_{1}}{T_{1}} = \frac{P_{2}V_{2}}{T_{2}}

Substitute the values into above formula as follows.

\frac{P_{1}V_{1}}{T_{1}} = \frac{P_{2}V_{2}}{T_{2}}\\\frac{0.60 atm \times 61 L}{183 K} = \frac{1 atm \times V_{2}}{273.15 K}\\V_{2} = 54.63 L

Thus, we can conclude that the new volume of a 61 L sample at STP that is moved to 183 K and 0.60 atm is 54.63 L.

4 0
3 years ago
Given the following reaction and data, A + B → Products
natima [27]

Answer:

a. Rate = k×[A]

b. k = 0.213s⁻¹

Explanation:

a. When you are studying the kinetics of a reaction such as:

A + B → Products.

General rate law must be like:

Rate = k×[A]ᵃ[B]ᵇ

You must make experiments change initial concentrations of A and B trying to find k, a and b parameters.

If you see experiments 1 and 3, concentration of A is doubled and the Rate of the reaction is doubled to. That means a = 1

Rate = k×[A]¹[B]ᵇ

In experiment 1 and to the concentration of B change from 1.50M to 2.50M but rate maintains the same. That is only possible if b = 0. (The kinetics of the reaction is indepent to [B]

Rate = k×[A][B]⁰

<h3>Rate = k×[A]</h3>

b. Replacing with values of experiment 1 (You can do the same with experiment 3 obtaining the same) k is:

Rate = k×[A]

0.320M/s = k×[1.50M]

<h3>k = 0.213s⁻¹</h3>

6 0
3 years ago
5
andriy [413]

Answer:

reaction 1 and reaction 4 both are decomposition reactions

while reaction 2 is double displacement reaction and reaction 3 and 5 are combination reactions

5 0
3 years ago
A gas is collected at 20.0 °C and 725.0 mm Hg. When the temperature is
krek1111 [17]

Answer:

676mmHg

Explanation:

Using the formula;

P1/T1 = P2/T2

Where;

P1 = initial pressure (mmHg)

P2 = final pressure (mmHg)

T1 = initial temperature (K)

T2 = final temperature (K)

According to the information provided in this question;

P1 = 725.0mmHg

P2 = ?

T1 = 20°C = 20 + 273 = 293K

T2 = 0°C = 0 + 273 = 273K

Using P1/T1 = P2/T2

725/293 = P2/273

Cross multiply

725 × 273 = 293 × P2

197925 = 293P2

P2 = 197925 ÷ 293

P2 = 676mmHg.

The resulting pressure is 676mmHg

3 0
3 years ago
Which property of water causes water drops to bead on a freshly waxed car?
astraxan [27]

Answer:

Cohesive forces are greater than adhesive forces  

Step-by-step explanation:

The attractive forces between water molecules and the wax on a freshly-waxed car (adhesive forces) are quite weak.

However, there are strong attractive forces (cohesive forces) between water molecules.

The water molecules are only weakly attracted to the wax, so the cohesive forces pull the water molecules together to form beads .

3 0
3 years ago
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