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trasher [3.6K]
3 years ago
11

How do I do question number 3? And what is the answer?

Chemistry
1 answer:
shutvik [7]3 years ago
3 0

Answer:

60.02 g.

Explanation:

  • It is clear from the balanced equation:

<em>Mg + 2HCl → MgCl₂ + H₂. </em>

that 1.0  mole of Mg reacts with 2.0 moles of HCl to produce 1.0 mole of MgCl₂ and 1.0 moles of H₂.

  • 20.0 g of Mg reacts with excess HCl. To calculate the no. of grams of HCl that reacted, we should calculate the no. of moles of Mg:

<em>no. of moles of Mg = mass/atomic mass</em> = (20.0 g)/(24.3 g/mol) = 0.823 mol.

  • From the balanced equation; every 1.0 mol of Mg reacts with 2 moles of HCl.

∴ 0.833 mol of Mg will react with (2 x 0.833 mol = 1.646 mol) of HCl.

<em>∴ The mass of reacted HCl = no. of moles x molar mass</em> = (1.646 mol)(36.46 g/mol) = <em>60.02 g.</em>

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How many grams of water can be produced in the combination of
mel-nik [20]

If 14 grams of hydrogen reacted with 24.7 grams of oxygen 27.7875 grams of water will be formed.

Explanation:

2H2+O2----------->2H2O.

  • From the above equation, we can say that 4g of Hydrogen will react with 32 g of oxygen.
  • In this question, Hydrogen is in excess amount.
  • 32 g of Oxygen will react with = 4 g of H2.
  • Therefore 24.7g of Oxygen will react with =24.7x4/32= 3.0875 g H2.  
  • The remaining 10.9125g of H2 will be left unreacted.
  • Therefore the amount of water formed=(24.7+3.0875)=27.7875 g

7 0
3 years ago
The alkali metals react with the halogens to form ionic metal halides. what mass of potassium chloride forms when 5.11 l of chlo
ale4655 [162]
<span>ideal gas law: PV = nRT so .....</span><span> V = PV/(RT) </span>
<span>
Initial number of moles of Cl, n = 0.943*5.11/(0.08206 × 286) mol = 0.2053 moles.
</span><span>
We know the molar mass of K (potassium) = 39.0 g/mol </span>
<span>sooo....
The Initial number of moles of K = 29.0 g/(39.0 g/mol) = 0.7436 moles</span>

<span>Find the balanced equation for the reaction : </span><span>2K + Cl2 → 2KCl </span>
<span>Mole ratio of K:Cl = 2:1 </span>

<span>So after the reaction, the amount of K needed = (0.2053 mol) × 2 = 0.4106 mol which is less than 0.7436 mol </span>
<span>
This means that K is in excess but Cl completely reacts. </span>

<span> So we know the mole ratio is  Cl:KCl = 1 : 2 
</span>
<span>Number of moles of Cl (completely) reacted = 0.2053 mol which means the n</span><span>umber of moles of KCl formed = (0.2053 mol) × 2 = 0.4106 mol </span>

<span>Molar mass of KCl = (39.0 + 35.5) g/mol = 74.5 g/mol </span>
<span>Mass of KCl formed = 0.4106 mol * 74.5 g/mol = 30.6 g</span>
4 0
3 years ago
How many moles of MgO are produced when .250 mol of Mg reacts completely with O2
nignag [31]

Answer:

0.250 moles of MgO are produced when 0.250 mol of Mg reacts completely with O₂

Explanation:

In first place, the balanced reaction between Mg and O₂ is:

2 Mg + O₂ ⇒ 2 MgO

By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of reactants and products participate in the reaction:

  • Mg: 2 moles
  • O₂: 1 mole
  • MgO: 2 moles

Then you can apply the following rule of three: if by reaction stoichiometry 2 moles of Mg produce 2 moles of MgO, 0.250 moles of Mg, how many moles of MgO will they form?

moles of MgO=\frac{0.250 moles of Mg*2 moles of MgO}{2 moles of Mg}

moles of MgO= 0.250

<u><em>0.250 moles of MgO are produced when 0.250 mol of Mg reacts completely with O₂</em></u>

3 0
3 years ago
In IR spectroscopy, we normally talk about "frequencies" when in reality we are referring to wavenumbers. What is the mathematic
Svetach [21]

Answer:

Here's what I get.

Explanation:

(b) Wavenumber and wavelength

The wavenumber is the distance over which a cycle repeats, that is, it is the number of waves in a unit distance.

\bar \nu = \dfrac{1}{\lambda}

Thus, if λ = 3 µm,

\bar \nu = \dfrac{1}{3 \times 10^{-6} \text{ m}}= 3.3 \times 10^{5}\text{ m}^{-1} = \textbf{3300 cm}^{-1}

(a) Wavenumber and frequency

Since

λ = c/f and 1/λ = f/c

the relation between wavenumber and frequency is

\bar \nu = \mathbf{\dfrac{f}{c}}

Thus, if f = 90 THz

\bar \nu = \dfrac{90 \times 10^{12} \text{ s}^{-1}}{3 \times 10^{8} \text{ m$\cdot$ s}^{-1}}= 3 \times 10^{5} \text{ m}^{-1} = \textbf{3000 cm}^{-1}

(c) Units

(i) Frequency

The units are s⁻¹ or Hz.

(ii) Wavelength

The SI base unit is metres, but infrared wavelengths are usually measured in micrometres (roughly 2.5 µm to 20 µm).

(iii) Wavenumber

The SI base unit is m⁻¹, but infrared wavenumbers are usually measured in cm⁻¹ (roughly 4000 cm⁻¹ to 500 cm⁻¹).

8 0
3 years ago
Energy can be changed from potential to kinetic.<br> A.True<br> B.False
vampirchik [111]

Answer:

An object has potential energy (stored energy) when it is not in motion. Once a force has been applied or it begins to move the potential energy changes to kinetic energy (energy of motion).

Therefore, true. (Also would u mind giving brainliest, you don't have to hehe)

6 0
2 years ago
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