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3 years ago

Although earth rorates on its axis as it orbits the sun what is true

1 answer:

4 0

Answer: Half of each hemisphere is lit, and the sunlight is centered on the equator. ... Earth's axis still points in the same direction, but now the North Pole seems to lean toward the Sun and is in sunlight. The June solstice marks the beginning of summer in the Northern hemisphere

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A chunk of copper has a volume of 1.45 mL and a mass of 12.93 grams. What is the density of the chunk of copper?

natta225 [31]

Answer:

$Density = 8.92 \ g/mL$

Explanation:

The equation for density is:

$Density = \frac{mass}{volume}$

We plug in the given values:

$Density = \frac{12.93 \ g}{1.45 \ mL}$

$Density = 8.92 \ g/mL$

7 0

3 years ago

Read 2 more answers

The pKa of lactic acid is 3.9. A lactate buffer will be useful from pH values ________. The pKa of lactic acid is 3.9. A lactate

Vedmedyk [2.9K]

Answer:

Explanation:

The usefulness of a buffer is its ability to resist changes in pH when small quantities of base or acid are added to it. This ability is the consequence of having both the conjugate base and the weak acid present in solution which will consume the added base or acid.

This capacity is lost if the ratio of the concentration of conjugate base to the concentration of weak acid differ by an order of magnitude. Since buffers having ratios differing by more will have their pH driven by either the weak acid or its conjugate base .

From the Henderson-Hasselbach equation we have that

pH = pKa + log [A⁻]/[HA]

thus

0.1 ≤ [A⁻]/[HA] ≤ 10

Therefore the log of this range is -1 to 1, and the pH will have a useful range of within +/- 1 the pKa of the buffer.

Now we are equipped to answer our question:

pH range = 3.9 +/- 1 = 2.9 through 4.9

7 0

3 years ago

The blank of an element is the average mass of all isotopes of that element

Oxana [17]

Atomic mass is the answer

if u hav any more questions in chemistry ask me! I am very good at chemistry.

6 0

3 years ago

Using the black numbers on the stopwatch to answer the questions.

Rus_ich [418]

Answer: the top one is 5.3 s and the bottom one is tenths of seconds

Explanation:

4 0

4 years ago

Read 2 more answers

An aqueous solution contains 0.29 M of benzoic acid (HA) and 0.16 M of sodium benzoate (A-). If the pH of this solution was meas

Inga [223]

Answer:

pKa = 4.89.

Explanation:

We can solve this problem by using the Henderson-Hasselbach equation, which states:

pH = pKa + log $\frac{[A^-]}{[HA]}$

In this case [A⁻] is the concentration of sodium benzoate and [HA] is the concentration of benzoic acid.

We input the given data:

4.63 = pKa + log $\frac{0.16}{0.29}$

And solve for pKa:

pKa = 4.89

3 0

3 years ago