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Nady [450]
4 years ago
6

ASAP MULTIPLE CHOICE WILL MARK BRAINLIEST

Chemistry
1 answer:
vredina [299]4 years ago
3 0
50 neutrons
explanation:
atomic number = protons
atomic mass = protons + neutrons
You might be interested in
Calcium is a group 2 element. Chlorine is a group 7 element. They form an ionic compound called
kondaur [170]

Answer:

CaCl2

Explanation:

For every calcium there's 2 chlorine

7 0
3 years ago
Balance this equation. Pb(NO3)2(aq)+NaCl(aq) -> NaNO3(aq)+PbCl2(s)
const2013 [10]

Answer:

Pb(NO3)2(aq) + 2NaCl(aq) -> 2NaNO3(aq)+PbCl2(s)

Explanation:

Pb(NO3)2(aq)+NaCl(aq) -> NaNO3(aq)+PbCl2(s)

This is how it starts out.

Left:

  • 2 NO3s
  • 1 Pb
  • 1 Na
  • 1 Cl

Right

  • 1 Na
  • 1 NO3
  • 1 Pb
  • 2 Cl

So the place to start with this equation is to bring the Cls up to 2

Pb(NO3)2(aq)+2NaCl(aq) -> NaNO3(aq)+PbCl2(s)

But the Nas are now out of kilter.

Pb(NO3)2(aq)+ 2NaCl(aq) -> NaNO3(aq)+PbCl2(s)

Now the right has a problem. There's only 1 Na

Pb(NO3)2(aq) + 2 NaCl(aq) -> 2NaNO3(aq)+PbCl2(s)

Check it out. It looks like we are done.

5 0
3 years ago
An unknown compound displays singlets at δ 2.1 ppm and 2.56 ppm in the ratio of 3:2. what is the structure of the compound?
olasank [31]

1) As can be seen from any 1H NMR chemical shift ppm tables, hydrogens which have δ values from 2ppm to 2.3ppm are hydrogens from carbon which is bonded to a carbonyl group. From this, we can conclude that our hydrogens belong to the type, but from 2 different alkyl groups because of 2 different signals.

 

2) So, one alkyl group is CH3 and second one can be CH or CH2.

 

3) If we know that ratio between two types of hydrogens is 3:2, it can be concluded that second alkyl group is CH2. 


4) Finally, we don't have any other signals and it indicates that part of the compound which continues on CH2 is exactly the same as the first part.

The ratio remains the same, 3:2 ie 6:4

7 0
3 years ago
a) Whatis the composition in mole fractions of a solution of benzene and toluene that has a vapor pressure of 35 torr at 20 °C?
iogann1982 [59]

Answer:

molar composition for liquid

xb= 0.24

xt=0.76

molar composition for vapor

yb=0.51

yt=0.49

Explanation:

For an ideal solution we can use the Raoult law.

Raoult law: in an ideal liquid solution, the vapor pressure for every component in the solution (partial pressure) is equal to the vapor pressure of every pure component multiple by its molar fraction.  

For toluene and benzene would be:

P_{B}=x_{B}*P_{B}^{o}

P_{T}=x_{T}*P_{T}^{o}

Where:

P_{B} is partial pressure for benzene in the liquid  

x_{B} is benzene molar fraction in the liquid  

P_{B}^{o} vapor pressure for pure benzene.  

The total pressure in the solution is:

P= P_{T}+ P_{B}

And  

1=x_{B}+x_{T}

Working on the equation for total pressure we have:

P=x_{B}*P_{B}^{o} + x_{T}*P_{T}^{o}

Since x_{T}=1-x_{B}

P=x_{B}*P_{B}^{o} + (1-x_{B})*P_{T}^{o}

We know P and both vapor pressures so we can clear x_{B} from the equation.

x_{B}=\frac{P- P_{T}^{o}}{ P_{B}^{o} - P_{T}^{o}}

x_{B}=\frac{35- 22}{75-22} = 0.24

So  

x_{T}=1-0.24 = 0.76

To get the mole fraction for the vapor we know that in the equilibrium:

P_{B}=y_{B}*P

y_{T}=1-y_{B}

So  

y_{B} =\frac{P_{B}}{P}=\frac{ x_{B}*P_{B}^{o}}{P}

y_{B}=\frac{0.24*75}{35}=0.51

y_{T}=1-0.51=0.49

Something that we can see in these compositions is that the liquid is richer in the less volatile compound (toluene) and the vapor in the more volatile compound (benzene). If we take away this vapor from the solution, the solution is going to reach a new state of equilibrium, where more vapor will be produced. This vapor will have a higher molar fraction of the more volatile compound. If we do this a lot of times, we can get a vapor that is almost pure in the more volatile compound. This is principle used in the fractional distillation.

7 0
3 years ago
When 25.0 mL of a solution of 1.4 x 10-3 M silver nitrate is mixed with 60.0 mL of a solution of 7.5 x 10-4 M sodium chloride a)
LUCKY_DIMON [66]
Step  one write  the  equation  for  dissociation  of  AgNO3  and  NaCl

that  is   AgNO3-------> Ag+   + NO3-

            NaCl-------->   Na+   +  Cl-
then  find  the  number  of  moles  of  each  compound
that  is  for   AgNO3  = ( 1.4 x10^-3 ) x  25/1000=  3.5  x10^-5  moles
                     Nacl=  (7.5  x10^-4)x 60/1000=  4.5  x10^-5  moles

from   mole  ratio  the  moles  of    Ag+=  3.5  x10^-5 moles  and  that  of  Cl-= 4.5  x10^-4 moles

  then find  the  total    volume  of  the  mixture
that  is  25ml  +  60 Ml  =85ml  =  0.085 liters

The  Ksp  of  Agcl =  (Ag+) (cl-),    let  the  concentration  of  Ag+ be  represented   by  x  and   also  the  concentration  be  represented by  x

ksp (1.8 x10^-10)  is  therefore=  x^2

find  the  square  root   x=1.342   x10^-5

Ag+ in  final  mixture  is =  moles  of  Ag+/total  volume - x
that is  {(3.5  x10^-5)/0.085}  -  1.342  x10^-5=3.98x10^-4


Cl-  in  the  final  mixture   is =(4.5  x10^-5 /0.085)  -  1.342  x10^-5= 5.16 x10^-4
4 0
4 years ago
Read 2 more answers
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