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meriva
3 years ago
12

Quantitative was to measure light intensity

Chemistry
2 answers:
Fofino [41]3 years ago
7 0
One candela per steradian is termed a lumen, which is the measure of light intensity people are most familiar with One foot candle is equivalent to one lumen per square foot
Norma-Jean [14]3 years ago
3 0
Whats the question tho??
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Some people are so good at their professions that other companies will try to recruit them?
Stella [2.4K]
Because they are good at their professions
7 0
3 years ago
An unknown metal has a mass of 86.8 g. When 5040 J of heat are added to the sample, the sample temperature changes by 64.7 ∘ C .
grandymaker [24]

Answer: The specific heat of the unknown metal is 0.897J/g^0C

Explanation:

The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

Q=m\times c\times \Delta T

Q = Heat absorbed=5040 Joules

m= mass of substance = 86.8 g

c = specific heat capacity = ?

Initial temperature of the water = T_i

Final temperature of the water = T_f

Change in temperature ,\Delta T=T_f-T_i=(64.7)^0C

Putting in the values, we get:

5040=86.8\times c\times 64.7^0C

c=0.897J/g^0C

The specific heat of the unknown metal is 0.897J/g^0C

4 0
3 years ago
Which of the following describes the boundaries created by earth's tectonic systems
Dvinal [7]
The earth's plates usually move in three different ways resulting in three different types of plate margins/ boundaries: CONVERGENT, DIVERGENT and TRANSFORM plate boundaries.

When plates move towards each other, they collide and this usually either results in the denser of the plates sliding below the other plate or both plates pushing against each other resulting in both plates being pushed upwards to form often times Fold Mountains.  This type of earth tectonics causes a CONVERGENT (destructive; because the collision of the plates results in loss of earth surface area) plate boundary to be formed.

Plates can also pull away from each other and in so doing creating space usually in the form of a fissure between the two moving plates. This fissure usually also for molten earth (magma) rising to the surface and closing the opening between the plates.  This type of earth tectonic is known to form DIVERGENT (constructive; because it usually results in new land being formed) plate margins.

Plates also slide against each other (side to side) thus not resulting in neither the destruction or creation of new land.  This kind of plate margin is known as the TRANSFORM plate boundary.


The diagram below helps to solidify the points made above.

8 0
3 years ago
If you have access to stock solutions of 1.00 M H3PO4, 1.00 M of HCl, and 1.00 M NaOH solution, (and distilled water of course),
garri49 [273]

Answer:

0.10L of 1.00M of H₃PO₄ and 0.1613L of 1.00M NaOH

Explanation:

The pKa's of phosphoric acid are:

H₃PO₄/H₂PO₄⁻ = 2.1

H₂PO₄⁻/HPO₄²⁻ = 7.2

HPO₄²⁻/PO₄³⁻ = 12.0

To make a buffer with pH 9.40 we need to convert all H₃PO₄ to H₂PO₄⁻ and an amount of H₂PO₄⁻ to HPO₄²⁻

To have a 50mM solution of phosphoures we need:

2L * (0.050mol / L) = 0.10 moles of H₃PO₄

0.10 mol * (1L / mol) = 0.10L of 1.00M of H3PO4

To convert the H₃PO₄ to H₂PO₄⁻ and to HPO₄²⁻ must be added NaOH, thus:

H₃PO₄ + NaOH → H₂PO₄⁻ + H₂O + Na⁺

H₂PO₄⁻ + NaOH → HPO₄²⁻ + H₂O + Na⁺

Using H-H equation we can find the amount of NaOH added:

pH = pKa + log [A⁻] / [HA] <em>(1)</em>

<em>Where [A-] is conjugate base, HPO₄²⁻ and [HA] is weak acid, H₂PO₄⁻</em>

<em>pH = 7.40</em>

<em>pKa = 7.20</em>

[A-] + [HA] = 0.10moles <em>(2)</em>

Replacing (2) in (1):

7.40 = 7.20 + log 0.10mol - [HA] / [HA]

0.2 = log 0.10mol - [HA] / [HA]

1.5849 = 0.10mol - [HA] / [HA]

1.5849 [HA] = 0.10mol - [HA]

2.5849[HA] = 0.10mol

[HA] = 0.0387 moles = H₂PO₄⁻ moles

That means moles of HPO₄²⁻ are 0.10mol - 0.0387moles = 0.0613 moles

The moles of NaOH needed to convert all H₃PO₄ in H₂PO₄⁻ are 0.10 moles

And moles needed to obtain 0.0613 moles of HPO₄²⁻ are 0.0613 moles

Total moles of NaOH are 0.1613moles * (1L / 1mol) = 0.1613L of 1.00M NaOH

Then, you need to dilute both solutions to 2.00L with distilled water.

4 0
3 years ago
Help on 2 and 3 due tomorrow pls help
Luda [366]

Answer:

2

b= they are grouped differently, but all the atoms are still there.

4 0
3 years ago
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