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3 years ago

RISD-QSA-SCI-CHEM-Units 7-12 Question: 1-1

Chemistry

1 answer:

ra1l [238]3 years ago

8 0

Answer:

0.02.55M

Explanation:

Concentration = moles/ volume(L)

10mL= 0.01L

Concentration (M)= 0.0255 mol / 0.01L

Concentration (M)= 0..255M

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The right line is a 90° clockwise rotation of the left line about the origin. Click the 90° clockwise button. Are these lines th

inessss [21]

Answer:

Switch the coordinates and change the sign of the second one by multiplying it by negative 1.

Explanation:

Here are some examples and a more general way to understand the problem.

Consider the point (1,1), a 90 degree rotation clockwise about the origin would move it into the 4th quadrant.

The new point is (1,-1) , similarly (-4,2)-> (2,4), (-4,3)-> (3,4)

We take a point p= (x,y) the the result of rotation p 90 clockwise about the orgin is a new point p'=(x',y')= (-y, x). .

In the case of p=(1,0) the new point is p'= (0, -1)

One can use a matrix where the first row is cos(a), sin(a) and the second row is

-sin(a) cos(a) for any clockwise rotation of a degrees about the origin.

If we let a=90 degrees we have

[0 1] as the first row and [-1 0] as the second row. So the matrix is:

|0 1|

|-1 0|

Call that matrix M

So a point p= (x,y) can be multiplied by M as follows Mp=p' where p' is the rotated point.

If p=(-4,2) then Mp

is M(-4,2) which after matrix multiplication means x'=0*-4+1*2=2 and y'=-1*-4+0*2=4

So p'=(2,4)

Try it with (1,0)

x'=1*0+0*1=0

y'=-1*1+0*1=-1

so p'=(0,-1) and (1,0)->(0,-1)

How about the point on the y axis (0,1), it should go to the point (1,0)

0*1+1*1=1 and -1*0+0*1 gives you the pont (1,0) ( we don't see the negative sign because -0 is just 0)

7 0

3 years ago

What is the pOH of a 0.150 M solution of potassium nitrite? (Ka HNO2 = 4.5 x 10−4 )

yanalaym [24]

Answer:

11.9 is the pOH of a 0.150 M solution of potassium nitrite.

Explanation:

Solution : Given,

Concentration (c) = 0.150 M

Acid dissociation constant = $k_a=4.5\times 10^{-4}$

The equilibrium reaction for dissociation of $HNO_2$ (weak acid) is,

$HNO_2+H_2O\rightleftharpoons NO_2^-+H_3O^+$

initially conc. c 0 0

At eqm. $c(1-\alpha)$ $c\alpha$ $c\alpha$

First we have to calculate the concentration of value of dissociation constant $(\alpha )$ .

Formula used :

$k_a=\frac{(c\alpha)(c\alpha)}{c(1-\alpha)}$

Now put all the given values in this formula ,we get the value of dissociation constant $(\alpha )$ .

$4.5\times 10^{-4}=\frac{(0.150\alpha)(0.150\alpha)}{0.150(1-\alpha)}$

$4.5\times 10^{-4} - 4.5\times 10^{-4}\alpha =0.150\alpha ^2$

$0.150\alpha ^2+4.5\times 10^{-4}\alpha-4.5\times 10^{-4}=0$

By solving the terms, we get

$\alpha=0.0533$

No we have to calculate the concentration of hydronium ion or hydrogen ion.

$[H^+]=c\alpha=0.150\times 0.0533=0.007995 M$

Now we have to calculate the pH.

$pH=-\log [H^+]$

$pH=-\log (0.007995 M)$

$pH=2.097\approx 2.1$

pH + pOH = 14

pOH =14 -2.1 = 11.9

Therefore, the pOH of the solution is 11.9

4 0

3 years ago

During the process of cellular respiration, water becomes oxygen.<br><br> True<br> False

White raven [17]

Answer:

False

Explanation:

Please mark brainlliest if you want and mark 5 stars please. Thank you and have a good day.

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3 years ago

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Which chemical reaction is the fastest?

pychu [463]

Answer:

C) drain cleaner fizzes up as it encounters blockages in a pipe

Explanation:

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3 years ago

Which of these processes take place at the same temperature?

Elodia [21]

Answer:

the person above me is very right

Explanation:

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3 years ago