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4 years ago

Is the night sky divided into contellations?Is a light-Year is a measurement of time?

Chemistry

1 answer:

inessss [21]4 years ago

5 0

-Yes, it's divided into 88 consellations.

-Yes, it's a unit of astronomical distance equivalent to the distance that light travels in one year

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1) What is the electron configuration of the element with 27 protons?

Romashka [77]

1) cobalt u can tell bc on a periodic table there is a small number that on cobalt is 27.

2) think that would be 11 bc in the 4th shell there can be up to 18 electrons

6 0

3 years ago

A 0.200 M solution of a weak acid, HA, is 9.4% ionized. Using this information, calculate Ka for HA.

slavikrds [6]

${ \qquad\qquad\huge\underline{{\sf Answer}}}$

Let's solve ~

Initial concentration of weak acid HA = 0.200 M

and dissociation constant ( ${ \alpha}$ ) is :

$\qquad \sf \dashrightarrow \: \alpha = \frac{dissociation \: \: percentage}{100}$

$\qquad \sf \dashrightarrow \: \alpha = \frac{9.4}{100} = 0.094$

Now, at initial stage :

$\textsf{ Conc of HA = 0.200 M}$

$\textsf{Conc of H+ = 0 M}$

$\textsf{Conc of A - = 0 M}$

At equilibrium :

$\textsf{Conc of HA = 0.200 - 0.094(0.200) = 0.200(1 - 0.094) = 0.200(0.906) = 0.1812 M}$

$\textsf{Conc of H+ = 0.094(0.200) = 0.0188 M}$

$\textsf{Conc of A - = 0.094(0.200) = 0.0188 M}$

Now, we know :

$\qquad \sf \dashrightarrow \: { K_a = \dfrac{[H+] [A-]}{[HA]}}$

( big brackets represents concentration )

$\qquad \sf \dashrightarrow \: { K_a = \dfrac{0.0188×0.0188}{0.1812}}$

$\qquad \sf \dashrightarrow \: { K_a = \dfrac{0.00035344}{0.1812}}$

$\qquad \sf \dashrightarrow \: { K_a \approx 0.00195 }$

$\qquad \sf \dashrightarrow \: {K_a \approx 1.9 × {10}^{-3} }$

7 0

2 years ago

Two 10g blocks, one of copper and one of iron, were heated from 300 K to 400K (a temperature difference of 100 K).

12345 [234]

1) 385 J

2) 450 J

Explanation:

The amount of energy that must be absorbed by a certain substance in order to increase its temperature by $\Delta T$ is given by the equation:

$Q=mC\Delta T$

where

m is the mass of the substance

C is its specific heat capacity

$\Delta T$ is the increase in temperature of the substance

For the block of copper in this problem, we have:

m = 10 g is the mass

$C=0.385 J/gK$ is the specific heat capacity of copper

$\Delta T=400-300 = 100 K$ is the change in temperature

So, the energy absorbed by the block of copper is

$Q=(10)(0.385)(100)=385 J$

Similarly for the block of iron, the energy absorbed by the iron is given by

$Q=mC\Delta T$

where

m is the mass of the block of iron

C is its specific heat capacity of iron

$\Delta T$ is the increase in temperature of the block

Here we have:

m = 10 g is the mass of the block

$C=0.450 J/gK$ is the specific heat capacity of iron

$\Delta T=400-300 = 100 K$ is the change in temperature

So, the energy absorbed by the block of iron is

$Q=(10)(0.450)(100)=450 J$

6 0

3 years ago

What is between the cornea and iris

joja [24]

The cornea is the outer clear, round structure that covers the Iris and the pupil. The Iris is the colored part of the eye.

4 0

4 years ago

Which of the following are physical properties of a penny? Choose all that are correct.

malfutka [58]

Slightly red in color is the only physical property

6 0

3 years ago