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zhenek [66]
2 years ago
11

Can someone please explain what to do it’s late at night and I need sleep but I forgot I had this homework please help me with a

few questions I’m desperate :(

Chemistry
1 answer:
Rus_ich [418]2 years ago
4 0

Answer:

1) it takes 13 second

2) 2100 miles

3) 40 miles / hours

4) 730 meters

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How is the periodic table used to predict the properties of an element?
Novosadov [1.4K]
There are many ways to predict the properties of an element here's one example.As you move from left to right the electron affinity and ionization  energy both increase .Since elements of the same family have similar characteristic,you can often  predict the properties of another element in its family
3 0
3 years ago
If a solution of HF (Ka=6.8×10−4) has a pH of 2.90, calculate the concentration of hydrofluoric acid.
fgiga [73]

Answer: 0.0023

Explanation:

I just answered this very same question. You can read my answer here: brainly.com/question/12077289.

1) First, you must write the balanced equilibrium equation, which will let you to determine the mole ratios of the different species in solution:

    HF ⇆ H⁺ + F⁻

Therefore, the mole ratio is: 1 HF: 1 H⁺ : 1  F⁻

2) Second, write the equilibrium constant of the acid, Ka, which will permit you to state the relationship of the concentrations in equilibrium:

        Ka = [H⁺] [F⁻] / [HF]

   [HF] is the searched concentration of the hydrofluoric acid

   From the mole ratio of the balanced chemical equation [H⁺] = [F⁻]

       Hence:

       Ka = [H⁺] [H⁺] / [HF] = [H⁺]² / [HF]

3) From the pH value you can calculate [H⁺],  using the definition:

  •    pH= - log [H⁺]
  •    Substitute: 2.90 = - log [H⁺]

 

 Clear [H⁺] using logarithm properties:

         [H^+]=10^{-2.90}=0.00126

4) Now you can substitute [H⁺] and the value of Ka in the equation for Ka:

   Ka = [H⁺]² / [HF] ⇒ [HF] = [H⁺]² / Ka = (0.00126)² / (6.8×10⁻⁴) = 0.00233.

Since the value of Ka has two significant figures, you must report the answer with two significan figures, i.e. 0.0023

7 0
3 years ago
In a combustion chamber, ethane (c2h6) is burned at a rate of 9 kg/h with air that enters the combustion chamber at a rate of 17
nekit [7.7K]

The percentage of excess air used during combustion process of ethane will be 37 %.

Burning, also known as combustion, would be a high-temperature highly exothermic chemical process that occurs when an oxidant, typically atmospheric oxygen, interacts with a fuel to generate oxidized, frequently gaseous products in a mixture known as smoke.

Calculation of percentage of air .

C_{2} H_{6} + (1-x)+a(O_{2} +3.76N_{2} )=bCO_{2}  + cH_{2} O + axO_{2}  + 3.76dN_{2} .

Mair=Mair/Rin

( MN)O_{2} + (MN)N_{2}÷ (MN)O_{2} + (MN)N_{2} +(MN)C_{2} H_{6} .

33 . 3.25(1-x) + 28 × 13.16(1-x) ÷ 33 × 3.25(1-x) + 28 × 13.16(1-x). + 30.1

= 176/176+8

X= 0.37

0.37 × 100

X= 37%

Therefore, the percentage of excess air used during combustion process of ethane will be 37 %.

To know more about combustion process

brainly.com/question/13153771

#SPJ4

3 0
1 year ago
A copper rod takes up 75 mL of space. With a density of 8.96 g/mL, what is the mass of the rod
pantera1 [17]
5.73 is the mass of the rod
5 0
2 years ago
Witch of these animals was unable to adapt to a warmer climate
ss7ja [257]
What  are the animals to choose from?

6 0
3 years ago
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