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ale4655 [162]
3 years ago
9

MCQ

Chemistry
1 answer:
andrey2020 [161]3 years ago
5 0

Answer:

1.014×10²³ atoms

Explanation:

Given data:

Volume of tungsten = 1.6 cm³

Density of tungsten = 19.35 g/cm³

Number of atoms of tungsten = ?

Solution:

First of all we will calculate the mass of tungsten.

density = mass/volume

by putting values,

19.35 g/cm³ = mass/1.6 cm³

Mass = 19.35 g/cm³× 1.6 cm³

Mass = 30.96 g

Number of moles of tungsten:

Number of moles = mass/molar mass

Number of moles = 30.96 g/ 183.84 g/mol

Number of moles = 0.1684 mol

1  mole contain 6.022×10²³ atoms.

0.1684 mol × 6.022×10²³ atoms / 1mol

1.014×10²³ atoms

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Bess [88]
2 nitrogen atoms, 4 hydrogen atoms and 3 oxygen atoms
8 0
3 years ago
What are the conditions needed for reaction to happen in aldehydes and ketones?
miv72 [106K]

Explanation:

You may not realise it, but you come across aldehydes and ketones many times a day. Take cakes and biscuits, for example. Their golden, caramelised crust is formed thanks to the Mailliard reaction. This is a process that occurs at temperatures above 140° C, when sugars with the carbonyl group in foods react with nucleophilic amino acids to create new and complex flavours and aromas.

Another example is formaldehyde. Correctly known as methanal, it is the most common aldehyde in industry. It has multiple uses, such as in tanning and embalming, or as a fungicide. However, we can also react it with different molecules to make a variety of more useful compounds. These include polymers, adhesives and precursors to explosives. But how do aldehydes and ketones react, and why?You should remember from Aldehydes and Ketones that they both contain the carbonyl functional group , . This is a carbon atom joined to an oxygen atom by a double bond. Let's take a closer look at it.

If we compare the electronegativities of carbon and oxygen, we can see that oxygen is a lot more electronegative than carbon.

7 0
3 years ago
HELPP!!!!!!!!!!
muminat

1. Mg + CuSO4 —> MgSO4 + Cu

=> Single displacement reaction

2. 2HCI + Mg(OH)2 —> MgCI2 + H2O

=> Acid - base reaction

3.AgNO3 + NaCI —> AgCI + NaNO3

=> Double displacement reaction

8 0
3 years ago
In which of the following compounds does the carbonyl stretch in the IR spectrum occur at the lowest wavenumber?
klio [65]

Answer:

a. Cyclohexanone

Explanation:

The principle of IR technique is based on the <u>vibration of the bonds</u> by using the energy that is in this region of the electromagnetic spectrum. For each bond, there is <em>a specific energy that generates a specific vibration</em>. In this case, you want to study the vibration that is given in the carbonyl group C=O. Which is located around 1700 cm-1.

Now, we must remember that the <u>lower the wavenumber we will have less energy</u>. So, what we should look for in these molecules, is a carbonyl group in which less energy is needed to vibrate since we look for the molecule with a smaller wavenumber.

If we look at the structure of all the molecules we will find that in the last three we have <u>heteroatoms</u> (atoms different to carbon I hydrogen) on the right side of the carbonyl group. These atoms allow the production of <u>resonance structures</u> which makes the molecule more stable. If the molecule is more stable we will need more energy to make it vibrate and therefore greater wavenumbers.

The molecule that fulfills this condition is the <u>cyclohexanone.</u>

See figure 1

I hope it helps!

4 0
4 years ago
At a certain temperature the rate of this reaction is second order in NH4OH with a rate constant of 34.1 M^-1s^-1: Suppose a ves
Tom [10]

Answer:

Time = 0.929s = 0.93s (2 s.f)

Explanation:

Rate constant, k = 34.1 M^-1s^-1

Initial Concentration, [A]o = 0.100M

Time = ?

Final Concentration [A] = 0.0240M

The parameters are represented in the following equation as;

1/[A] = kt + 1/[A]o

kt = 1/[A]  -  1/[A]o

kt = 1/0.0240 - 1/0.1

kt = 31.67

t = 31.67 / 34.1

t = 0.929s = 0.93s (2 s.f)

5 0
3 years ago
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