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2 years ago

Suppose you need to prepare 136.9 mL of a 0.315 M aqueous solution of NaCl.

Chemistry

1 answer:

Varvara68 [4.7K]2 years ago

4 0

Answer:

2.52 g NaCl

Explanation:

(Step 1)

To find the mass, you first need to find the moles NaCl. This value can be found using the molarity ratio:

Molarity = moles / volume (L)

After you convert mL to L, you can plug the given values into the equation and simplify to find moles.

136.9 mL / 1,000 = 0.1369 L

Molarity = moles / volume

0.315 M = moles / 0.1369 L

0.0431 = moles

(Step 2)

Now, you can use the molar mass to convert moles to grams.

Molar Mass (NaCl): 22.990 g/mol + 35.453 g/mol

Molar Mass (NaCl): 58.443 g/mol

0.0431 moles NaCl 58.443 g
------------------------------ x ------------------- = 2.52 g NaCl
1 mole

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The energy of a pendulum is recorded at different positions in the table below. Use the data in the table to determine the amoun

natta225 [31]

Answer:

36.55 J

Explanation:

PE = Potential energy

KE = Kinetic energy

TE = Total energy

The following data were obtained from the question:

Position >> PE >>>>> KE >>>>>> TE

1 >>>>>>>> 72.26 >> 27.74 >>>> 100

2 >>>>>>>> 63.45 >> x >>>>>>>> 100

3 >>>>>>>> 58.09 >> 41.91 >>>>> 100

The kinetic energy of the pendulum at position 2 can be obtained as follow:

From the table above, at position 2,

Potential energy (PE) = 63.45 J

Kinetic energy (KE) = unknown = x

Total energy (TE) = 100 J

TE = PE + KE

100 = 63.45 + x

Collect like terms

100 – 63.45 = x

x = 36.55 J

Thus, the kinetic energy of the pendulum at position 2 is 36.55 J.

7 0

3 years ago

Wetlands provide habitats for many living things because of their sheltered waters and

777dan777 [17]

The choices can be found elsewhere and as follows:

a. large supply of nutrients.
b. thick layer of mud.
c. lack of insects
d. ability to prevent floods.

I believe the correct answer is option A. Wetlands provide habitats for many living things because of their sheltered waters and large supply of nutrients. Hope this answers the question.

7 0

3 years ago

Read 2 more answers

Determine the enthalpy change when 23.5 g of carbon is reacted with oxygen according to the reaction C(s) + O2(g) CO2(g) delta H

xeze [42]

We are provided with the amount of energy released when one mole of carbon reacts. We mus first convert the given mass of carbon to moles and then compute the energy released for the given amount.

Moles = mass / atomic mass
Moles = 23.5 / 12
Moles = 1.96 moles

One mole releases 394 kJ/mol
1.96 moles will release:
394*1.96
= 772.24

The enthalpy change of the reaction will be -772.24 kJ

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3 years ago

Silicon carbide (SiC) is an important ceramic material made by reacting sand (silicon dioxide, SiO2) with powdered carbon at a h

makkiz [27]

Answer:

Percent yield of SiC is 77.0%.

Explanation:

Balanced reaction: $SiO_{2}+3C\rightarrow SiC+2CO$

Molar mass of SiC = 40.11 g/mol

Molar mass of $SiO_{2}$ = 60.08 g/mol

So, 100.0 kg of $SiO_{2}$ = $\frac{100.0\times 10^{3}}{60.08}$ moles of $SiO_{2}$ = 1664 moles of $SiO_{2}$

According to balanced equation, 1 mol of $SiO_{2}$ produces 1 mol of SiC

Therefore, 1664 moles of $SiO_{2}$ produce 1664 moles of SiC

Mass of 1664 moles of SiC = $(1664\times 40.11)g$ = 66743g = 66.74 kg (4 sig. fig.)

Percent yield of SiC = [(actual yield of SiC)/(theoretical yield of SiC)] $\times 100$ %

= $\frac{51.4kg}{66.74kg}\times 100$ %

= 77.0%

4 0

3 years ago

What is the average atomic mass of all of the naturally occurring isotopes of nickel in amu?

My name is Ann [436]

In general chemistry, isotopes are substances that belong to one specific element. So, they all have the same atomic numbers. But they only differ in the mass numbers, or the number of protons and neutrons in the nucleus. In a nutshell, they only differ in the number of neutrons.

For Nickel, there are 5 naturally occurring isotopes. Their identities, masses and relative abundance are listed below

Isotope Abundance Atomic Mass
Ni-58 68.0769% 57.9353 amu
Ni-60 26.2231% 59.9308 amu
Ni-61 1.1399 % 60.9311 amu
Ni-62 3.6345% 61.9283 amu
Ni-64 0.9256% 63.9280 amu

To determine the average atomic mass of Nickel, the equation would be:
Average atomic mass = ∑Abundance×Atomic Mass

Using the equation, the answer would be:
Average atomic mass = 57.9353(68.0769%) + 59.9308(26.2231%) + 60.9311(1.1399%) + 61.9283(3.6345%) + 63.9280(0.9256%)

Average atomic mass = 58.6933 amu

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4 years ago