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lesantik [10]
3 years ago
12

Find the natural abundance of Si-30.

Chemistry
1 answer:
nataly862011 [7]3 years ago
5 0
<span> First you need to know how many isotopes there are of silicon, and its average atomic units (look at periodic table). Then make up a system of equations to solve for it. Theres 3 stable silicon isotopes (28, 29, 30) so you will need to have 3 equations. You must be given the percent abundance of at least one of the isotopes to solve because here I can only see 2 equations (numbered down below) set x = percent abundance of si-28 y = percent abundance of si-29 z = percent abundance of si-30 since all of silicon atoms account for 100% of all silicon: x + y + z = 100% = 1 therefore: 1) x = 1 - y - z You also have 2) 28x + 29y + 30z = average atomic mass you can substitute x so that equation becomes: 28 (1 - y - z) + 29y + 30z = average atomic mass See how you have 2 variables here? You cant go on until you know the value of one isotope already or you have given a clue which you can derive the third equation</span>
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a sample of helium occupies a volume of 101.2 mL at a pressure of 790 mmHg. at what pressure would the volume be 120 mL?
AveGali [126]

Answer : The final pressure will be, 666.2 mmHg

Explanation :

Boyle's Law : It is defined as the pressure of the gas is inversely proportional to the volume of the gas at constant temperature and number of moles.

P\propto \frac{1}{V}

or,

P_1V_1=P_2V_2

where,

P_1 = initial pressure = 790 mmHg

P_2 = final pressure = ?

V_1 = initial volume = 101.2 mL

V_2 = final volume = 120 mL

Now put all the given values in the above equation, we get:

790mmHg\times 101.2mL=P_2\times 120mL

P_2=666.2mmHg

Therefore, the final pressure will be, 666.2 mmHg

6 0
3 years ago
What kind of sport do you have interest the most and explain why? <br>​
lidiya [134]

Answer

Gymnastics

Explanation:

for the simple fact that they do cool stuff

7 0
3 years ago
29. If a walnut is burned in a
harkovskaia [24]

Energy were released from the walnut, q = 1,673.6 J

<h3>Equation :</h3>

To find the energy using formula,

q = mcΔt

where,

q is charge

m is mass

c is specific heat of water

Δt is change in temperature

So, given

t₁ = 50°C

t₂ = 60°C

m = 40g

c = 4.184 J/g

Now putting the values known,

We get,

q = mc(t₂ - t₁)

q = 40g x 4.184 J/g x  (60 - 50)

q = 167.36 J x 10

q = 1,673.6 J

<h3>What is heat energy?</h3>

Heat is the thermal energy that is transferred when two systems with different surface temperatures come into contact. Heat is denoted by the letters q or Q and is measured in Joules.

To know more about specific heat :

brainly.com/question/11297584

#SPJ9

8 0
1 year ago
How many electrons are contained in a co3+ ion
Mumz [18]
The atomic number of cobalt, CO is 27. Since, the cobalt that you asked is in ion. The number of electrons should be 27-3 --> *24* Reasons being that cobalt has donated/given away 3 electrons.
7 0
3 years ago
One mole of a metallic oxide reacts with one mole of hydrogen to produce two moles of the pure metal
WARRIOR [948]

Answer:

Lithium oxide, Li₂O.  

Explanation:

Hello!  

In this case, according to the given amounts, it is possible to write down the chemical reaction as shown below:

M_2O+H_2\rightarrow 2M+H_2O  

Which means that the metallic oxide has the following formula: M₂O. Next, we can set up the following proportional factors according to the chemical reaction:

5.00gM_2O*\frac{1molM_2O}{(2*X+16)gM_2O}*\frac{2molM}{1molM_2O}*\frac{XgM}{1molM}=2.32gM  

Thus, we perform the operations in order to obtain:

\frac{10X}{(2X+16)}=2.32  

So we solve for x as shown below:

10X=2.32(2X+16)\\\\10X=4.64X+37.12\\\\X=\frac{37.12}{10-4.64}\\\\X= 6.93g/mol  

Whose molar mass corresponds to lithium, and therefore, the metallic oxide is lithium oxide, Li₂O.  

Best regards!

8 0
3 years ago
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