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umka21 [38]
2 years ago
14

unknown substance's mass: 75.0g, unknown substances molar mass = 150.0 g/mol, Hfus = 5.0x10^3 J/mol, Hvap = 1.00 x 10^4 J/mol, u

nknown substance's specific heat (liquid) = 2.2 J/g, unknown substance's specific heat (gas) = 4.8 J/g, unknown substances's specific heat (solid) = 5.0 J/g; Calculate the amount of heat (in J) for the unkown sample as it is heated at a constant rate from 10.0c to 25.0c as it passes through each of the following regions: region uv
Chemistry
2 answers:
Dimas [21]2 years ago
6 0

Answer:

kkajqjjqjqjnqnqnqjqjq

Leni [432]2 years ago
4 0
These are the answers hope this helps

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Why is governmental funding of research important?
nordsb [41]

Answer:

D. The government determines what is right & wrong for everyone

Explanation:

3 0
2 years ago
A 5g piece of aluminum foil (c=0.897) at 100°C is dropped into a 25g container of water (c=4.184) at 20°C. What is the final tem
jeyben [28]

Answer:

23.6°C

Explanation:

use delta h method

5 0
3 years ago
Which of these is indication that a chemical reaction has occurred?
trasher [3.6K]
B.melting of a substance
3 0
3 years ago
Read 2 more answers
formic acid buffer containing 0.50 M HCOOH and 0.50 M HCOONa has a pH of 3.77. What will the pH be after 0.010 mol of NaOH has b
HACTEHA [7]

Answer:

pH = 3.95

Explanation:

It is possible to calculate the pH of a buffer using H-H equation.

pH = pka + log₁₀ [HCOONa] / [HCOOH]

If concentration of [HCOONa] = [HCOOH] = 0.50M and pH = 3.77:

3.77 = pka + log₁₀ [0.50] / [0.50]

<em>3.77 = pka</em>

<em />

Knowing pKa, the NaOH reacts with HCOOH, thus:

HCOOH + NaOH → HCOONa + H₂O

That means the NaOH you add reacts with HCOOH producing more HCOONa.

Initial moles of 100.0mL = 0.1000L:

[HCOOH] = (0.50mol / L) ₓ 0.1000L = 0.0500moles HCOOH

[HCOONa] = (0.50mol / L) ₓ 0.1000L = 0.0500moles HCOONa

After the reaction, moles of each species is:

0.0500moles HCOOH - 0.010 moles NaOH (Moles added of NaOH) = 0.0400 moles HCOOH

0.0500moles HCOONa + 0.010 moles NaOH (Moles added of NaOH) = 0.0600 moles HCOONa

With these moles of the buffer, you can calculate pH:

pH = 3.77 + log₁₀ [0.0600] / [0.0400]

<h3>pH = 3.95</h3>

3 0
3 years ago
Molecules have ionization energies, just like atoms do. The ionization energy for molecular oxygen, for example, is 1314 kJ/mol.
taurus [48]

Answer:

91.1835 nm

Explanation:

Given that the ionization energy of the oxygen molecule = 1314 kJ/mol

It means that

1 mole of oxygen molecules can be ionized by the energy = 1314 kJ = 1314000 J

1 mole of molecules contains 6.022 × 10²³ atoms

So,

6.022 × 10²³ atoms of oxygen molecules can be ionized by the energy = 1314000 J

1 atom require \frac{1314000}{6.022\times 10^{23}}\ J of energy

Energy = 2.18\times 10^{-18}\ J

Also

E=\frac {h\times c}{\lambda}

Where,  

h is Plank's constant having value 6.626\times 10^{-34}\ Js

c is the speed of light having value 3\times 10^8\ m/s

\lambda is the wavelength

So,

\lambda=\frac {h\times c}{E}

\lambda=\frac{6.626\times 10^{-34}\times 3\times 10^8}{2.18\times 10^{-18}}\ m

\lambda=91.1835\times 10^{-9}}\ m

Also,

1\ nm=10^{-9}}\ m

So, wavelength = 91.1835 nm

6 0
3 years ago
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