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USPshnik [31]
3 years ago
7

Hurry need answer as soon as possible please . Compare the type of change that occurs when a substance melts and when a substanc

e is set on fire. Use complete sentences to justify the type of change that occurs.
Chemistry
1 answer:
tamaranim1 [39]3 years ago
5 0

Answer:

Explanation:

A substance melting is a physical change and the properties of the substance will remain same, only that the substance will just become liquid.

On the other hand, burning is a chemical change which produces an entirely new compount(in most cases, ash) which does not have the same properties as the original object

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How many ions are in 1.50 grams of Na+?
Jobisdone [24]

Answer:

= 0.0652 moles

Explanation:

I hope it helps you

7 0
2 years ago
If the actual yield of a reaction is 37.6 g while the theoretical yield is 112.8 g what is the percent yield
Zigmanuir [339]
<h2>Hello!</h2>

The answer is:

The percent yield of the reaction is 32.45%

<h2>Why?</h2>

To calculate the percent yield, we have to consider the theoretical yield and the actual yield. The theoretical yield as its name says is the yield expected, however, many times the difference between the theoretical yield and the actual yield is notorious.

We are given that:

ActualYield=37.6g\\TheoreticalYield=112.8g

Now, to calculate the percent yield, we need to divide the actual yield by the theoretical and multiply it by 100.

So, calculating we have:

PercentYield=\frac{ActualYield}{TheoreticalYield}*100\\\\PercentYield=\frac{37.6g}{112.8g}*100=0.3245*100=32.45(percent)

Hence, we have that the percent yield of the reaction is 32.45%.

Have a nice day!

8 0
3 years ago
Read 2 more answers
If PbI2(s) is dissolved in 1.0MNaI(aq) , is the maximum possible concentration of Pb2+(aq) in the solution greater than, less th
fredd [130]

Answer:

\mathbf{s =\sqrt [3]{\dfrac{K_{sp}}{4}}}

Less than the concentration of Pb2+(aq) in the solution in part ( a )

Explanation:

From the question:

A)

We assume that s to be  the solubility of PbI₂.

The equation of the reaction is given as :

PbI₂(s) ⇌ Pb²⁺(aq) + 2I⁻(aq); Ksp = 7 × 10⁻⁹

 [Pb²⁺] =   s

Then [I⁻] = 2s

K_{sp} =\text{[Pb$^{2+}$][I$^{-}$]}^{2} = s\times (2s)^{2} =  4s^{3}\\s^{3} = \dfrac{K_{sp}}{4}\\\\s =\mathbf{ \sqrt [3]{\dfrac{K_{sp}}{4}}}\\\\\text{The mathematical expressionthat can be used to determine the value of  }\mathbf{s =\sqrt [3]{\dfrac{K_{sp}}{4}}}

B)

The Concentration of Pb²⁺  in water is calculated as :

\mathbf{s =\sqrt [3]{\dfrac{K_{sp}}{4}}}

\mathbf{s =\sqrt [3]{\dfrac{7*10^{-9}}{4}}}

\mathbf{s} =\sqrt[3]{1.75*10^{-9}}

\mathbf{s} =\mathbf{1.21*10^{-3}  \ mol/L }

The Concentration of Pb²⁺  in 1.0 mol·L⁻¹ NaI

\mathbf{PbCl{_2}}  \leftrightharpoons    \ \ \ \ \ \ \  \mathbf{Pb^{2+}}   \ \ \ \  \ +   \ \  \ \ \ \ \ \mathbf{2 I^-}

                             \ \ \ \ \ \ \  \ \   \ \  \ \ \ \ \ \ \  \mathbf0}   \ \ \ \  \ \ \ \ \ \   \ \ \ \ \ \mathbf{1.0}

                            \ \ \ \ \ \ \ \ \ \ \ \ \ \    \ \ \ \ \  \mathbf{+x}   \ \ \ \  \    \ \  \ \ \ \ \ \mathbf{+2x}

                            \ \ \ \ \ \ \ \ \ \ \ \ \ \    \ \ \ \ \  \mathbf{+x}   \ \ \ \  \    \ \  \ \ \ \ \ \mathbf{1.0+2x}

The equilibrium constant:

K_{sp} =[Pb^{2+}}][I^-]^2 \\ \\ K_{sp} = s*(1.0*2s)^2 =7*1.0^{-9} \\ \\ s = 7*10^{-9} \ \  m/L

It is now clear that maximum possible concentration of Pb²⁺ in the solution is less than that in the solution in part (A). This happens due to the  common ion effect. The added iodide ion forces the position of equilibrium to shift to the left, reducing the concentration of Pb²⁺.

3 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
3 years ago
Read 2 more answers
Most metamorphosis processes take place
Ugo [173]

Most metamorphic processes take place a few kilometers below Earth's surface. Metamorphic processes result due to intense heat and high pressure below the Earth's surface. Also, metamorphism can occur on two scales, contact and regional.

8 0
3 years ago
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