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Olegator [25]
3 years ago
9

You need to make a very dilute solution of sodium phosphate dihydrate (MW 142 g/mol, FW 178 g/mol). How many grams of sodium pho

sphate dihydrate do you need to make 500 mL of a 2 M stock solution? How many mL of the stock solution do you need to make 100 mL of a 5 mM solution?
Physics
1 answer:
dlinn [17]3 years ago
6 0

Answer:

first question is 178 g of sodium phosphate dihydrate. second question is 0.25 mL

Explanation:

To know the number of grams from the number of moles (0.5L*2mol/L)= 1mol. 1 mol is equal to 178 g. Second question mL of the stock is obtained from (0.1L*5.0^-3mol/L)/2mol/L.

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A ray of light travels from a glass-to-liquid interface at an angle of 35.0º. Indices of refraction for the glass and liquid are
UkoKoshka [18]

Answer:

The angle of refraction for the ray moving through the liquid is = 32.3°

Explanation:

Refractive index of liquid (n₁/n₂) = sini/sinr

∴                 n₁/n₂ = sini/sinr ................ equation 1

n₁ = index of refraction for glass, n₂ = index of refraction for liquid

Where i = incident angle of the first medium, r = angle of refraction or angle in the second medium.

Since the light ray is traveling from glass - to - liquid,  the first medium is glass and the second medium is liquid. and the refractive index will be that liquid with respect to glass.

using the equation,

n₁/n₂ = sini/sinr

i = 35° , n₁ = 1.52, n₂= 1.63

Making sinr the subject of the equation above,

sinr = sini/(n₁/n₂)

sinr = sin35(1.52)/1.63

sinr =0.574(1.52)/1.63

sinr = 0.535

Taking the sin inverse of both side of the equation

sin⁻¹(sinr) = sin⁻¹(0.535)

∴ r = 32.3°

The angle of refraction for the ray moving through the liquid is = 32.3°

The right option is (b). 32.3°

5 0
3 years ago
A student is investigating potential and kinetic energy by stretching a spring across a table when the student lets go the sprin
nikitadnepr [17]

Answer: could be B.

Explanation:

7 0
2 years ago
Help please <br>the question is in the picture ​
zavuch27 [327]

Answer:

The SI unit of power is the watt

Explanation:

7 0
3 years ago
Read 2 more answers
A car traveling at 30 m/s drives off a cliff that is 50 meters high? How far away does it land?
Semenov [28]

Answer:

The maximum range R_{max}= 132. 72 m

Explanation:

Given,

The initial velocity of the car, u = 30 m/s

The height of the cliff, h = 50 m

Let the car drives off the cliff with a horizontal velocity of 30 m/s.

The formula for a projectile that is projected from a height h from the ground is given by the relation

                                R_{max}= \frac{u}{g}\sqrt{u^{2} + 2gh }  m

Where,

                          g - acceleration due to gravity

Substituting the values in the above equation

                   R_{max}= \frac{30}{9.8}\sqrt{30^{2} + 2X9.8X50 }  

                                          = 132.72  m

Hence, the car lands at a distance, R_{max}= 132. 72 m            

3 0
3 years ago
If the moment acting on the cross section is M=630N⋅m, determine the maximum bending stress in the beam. Express your answer to
-BARSIC- [3]

Answer:

2.17 Mpa

Explanation:

The location of neutral axis from the top will be

\bar y=\frac {(240\times 25)\times \frac {25}{2}+2\times (20\times 150)\times (25+(\frac {150}{2}))}{(240\times 25)+2\times (20\times 150)}=56.25 mm

Moment of inertia from neutral axis will be given by \frac {bd^{3}}{12}+ ay^{2}

Therefore, moment of inertia will be

\frac {240\times 25^{3}}{12}+(240\times 25)\times (56.25-25/2)^{2}+2\times [\frac {20\times 150^{3}}{12}+(20\times 150)\times ((25+150/2)-56.25)^{2}]=34.5313\times 10^{6} mm^{4}}

Bending stress at top= \frac {630\times 10^{3}\times (175-56.25)}{34.5313\times 10^{6}}=2.1665127\approx 2.17 Mpa

Bending stress at bottom=\frac {630\times 10^{3}\times 56.25}{34.5313\times 10^{6}}=1.026242858\approx 1.03 Mpa

Comparing the two stresses, the maximum stress occurs at the bottom and is 2.17 Mpa

8 0
3 years ago
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