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4 years ago

Why can Sirius be seen in the night sky? Thank you who ever answers

Chemistry

1 answer:

ra1l [238]4 years ago

7 0

Answer:

Because the star has a higher luminosity/intrinsic brightness than other stars.

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Please help me guys to solve this problem!

steposvetlana [31]

(a) distance measured with metre rule or tape rule

time measured with stopwatch/ stop clock/ timer

Average speed = total distance / time

(b) (i) decrease in speed

(ii) Change in speed = a * t

4.5 m/s

<em>hope this helps......</em>

6 0

3 years ago

Calculate ΔH and ΔStot when two copper blocks, each of mass 10.0 kg, one at 100°C and the other at 0°C, are placed in contact in

ira [324]

Explanation:

The given data is as follows.

m = 10.0 kg = 10,000 g (as 1 kg = 1000 g)

Initial temp. of block 1, $T_{1} = 100^{o}C$ = (100 + 273) K = 373 K

Initial temp. of block 2, $T_{2} = 0^{o}C$ = (0 + 273) K = 273 K

So, heat released by block 1 = heat gained by block 2

$mC \Delta T = mC \times \Delta T$

$10000 g \times 0.385 \times (T_{f} - 100)^{o}C = 10000 g \times 0.385 \times (0 - T_{f})^{o}C$

$T_{f} - 100^{o}C = 0^{o}C - T_{f}$

$2T_{f} = 100^{o}C$

$T_{f} = 50^{o}C$

Convert temperature into kelvin as (50 + 273) K = 323 K.

Also, we know that the relation between enthalpy and temperature change is as follows.

$\Delta H = mC \Delta T$

= $10000 g \times 0.385 J/K g \times 323 K$

= 1243550 J

or, = 1243.5 kJ

Now, calculate entropy change for block 1 as follows.

$\Delta S_{1} = mC ln \frac{T_{f}}{T_{i}}$

= $10000 g \times 0.385 J/K g \times ln \frac{323}{373}$

= $10000 g \times 0.385 J/K g \times -0.143$

= -554.12 J/K

Now, entropy change for block 2 is as follows.

$\Delta S_{2} = mC ln \frac{T_{f}}{T_{i}}$

= $10000 g \times 0.385 J/K g \times ln \frac{323}{273}$

= $10000 g \times 0.385 J/K g \times 0.168$

= 647.49 J/K

Hence, total entropy will be sum of entropy change of both the blocks.

$\Delta S_{total} = \Delta S_{1} + \Delta S_{2}$

= -554.12 J/K + 647.49 J/K

= 93.37 J/K

Thus, we can conclude that for the given reaction $\Delta H$ is 1243.5 kJ and $\Delta S_{total}$ is 93.37 J/K.

6 0

3 years ago

If 3. 5 grams of ni are reacted with excess oxygen to form nickel oxide unser standard state conditions, what is the entropy cha

Mashutka [201]

Entropy Change is the measure of the randomness of the thermodynamic system. The entropy change for the reaction is -49.3 J/K.

<h3>What is the change in entropy?</h3>

Entropy change is the ratio of the heat transfer of the system to the absolute temperature of the system.

The entropy of nickel = 182.1 J/mol. K

The entropy of oxygen = 205.0 J/mol. K

The entropy of nickel oxide = 37.99 J/mol. K

Entropy change is calculated as:

$\begin{aligned}\Delta \rm S &= 2(37.99)-2(182.1)-205\\\\&= 75.98 - 364.2 - 205\\\\&= -493.22 \end{aligned}$

Therefore, -49.3 J/K is the entropy change.

Learn more about entropy change here:

brainly.com/question/1301642

#SPJ4

8 0

2 years ago

Ecstasy is one example of which of the following?

yarga [219]

Answer:

Narcotics

I think ans is

7 0

3 years ago

Read 2 more answers

How many atoms are in 0.075 mol of titanium?

Annette [7]

The mass of titanium is = 47,867 g/1mol

Applying the rule of avrogado

1mol _______ 6,023 × 10^(23) at

0,075mol ___ x

X . 1mol = 0,075mol . 6,023 . 10^(23)at

X = 0,075 . 6,023 . 10^(23) at

X = 4,51 . 10^(22) atoms

Hope this helps

7 0

4 years ago

Read 2 more answers