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Angelina_Jolie [31]
4 years ago
15

the element copper cu has two naturally occurring isotopes. 69% of all coopers consist of atom with 34 neutrons, 31% of all samp

les with 36 neutrons. calculate the average atomic weight of cooper atoms

Chemistry
1 answer:
solniwko [45]4 years ago
6 0
Answer : Average atomic weight of copper atoms will be 63.62 u. 

Explanation : For calculating average atomic weight for any given atom we use this formula,

m = Σm_{i} X % abundance

where, m - avg atomic mass of isotope.
and m_{i} - mass of isotope

on solving we get, 
m = [63 u X (69/100)] + [65 u X (31/100)] = 63.62 u.

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What value was there in predicting the properties for gaps in Mendeleev's table?
guapka [62]

helped discover elements down the line

6 0
3 years ago
Aluminum reacts with oxygen to produce aluminum oxide which can be used as an adsorbent, desiccant or catalyst for organic react
pishuonlain [190]
The balance chemical equation is as follow,

                                        2 Al  +  3 O₂   →   Al₂O₃

Aluminium is the Limiting Reagent,
As,
                                107.92 g Al required  =  96 g of O₂
Then,
                          82.49 g of Al will require  =  X g of O₂
Solving for X,
                                    X  =  (82.49 g × 96 g) ÷ 107.92 g

                                    X  =  73.37 g of O₂
But,
     We are provided with 117.65 g of O₂, So, it is provided in excess and 44.28 g of it will remain unreacted.

Solving for Amount of Al₂O₃ formed,
As,
                        107.92 g of Al produced  =  203.92 g of Al₂O₃
Then,
                      82.49 g of Al will produce  =  X g of Al₂O₃
SOlving for X,
                                          X  =  (82.49 g ×  203.92 g) ÷ 107.92

                                          X  =  155.86 g of Al₂O₃
8 0
4 years ago
A food substance kept at 0°C becomes rotten (as determined by a good quantitative test) in 8.3 days. The same food rots in 10.6
ZanzabumX [31]

Answer:

1.   67.2 kJ/mol

Explanation:

Using the derived expression from Arrhenius Equation

In \ (\frac{k_2}{k_1}) = \frac{E_a}{R}(\frac{T_2-T_1}{T_2*T_1})

Given that:

time t_1 = 8.3 days = (8.3 × 24 ) hours = 199.2 hours

time t_2 = 10.6 hours

Temperature T_1 = 0° C = (0+273 )K = 273 K

Temperature T_2 = 30° C = (30+ 273) = 303 K

Rate = 8.314 J / mol

Since (\frac{k_2}{k_1}=\frac{t_2}{t_1})

Then we can rewrite the above expression as:

In \ (\frac{t_2}{t_1}) = \frac{E_a}{R}(\frac{T_2-T_1}{T_2*T_1})

In \ (\frac{199.2}{10.6}) = \frac{E_a}{8.314}(\frac{303-273}{273*303})

2.934 = \frac{E_a}{8.314}(\frac{30}{82719})

2.934 = \frac{30E_a}{687725.766}

30E_a = 2.934 *687725.766

E_a = \frac{2.934 *687725.766}{30}

E_a =67255.58 \ J/mol

E_a =67.2 \ kJ/mol

7 0
3 years ago
Clouds form when water vapor in the air condenses to form liquid water or ice crystals.
Gnoma [55]
Hey there!

I think it's true

Hope this helps!

Always remember, you are a Work Of Art! 
- Nicole <3 :)
6 0
3 years ago
How many atoms are in 1.204x10^22 moles of arsenic?
ra1l [238]

Answer:

<h2>0.02 moles </h2>

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

n =  \frac{N}{L} \\

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

We have

n =  \frac{1.204 \times  {10}^{22} }{6.02 \times  {10}^{23} }    \\  = 0.02

We have the final answer as

<h3>0.02 moles</h3>

Hope this helps you

7 0
3 years ago
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