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m_a_m_a [10]
2 years ago
8

The human skeleton is made mostly of hard blank tissue.

Chemistry
1 answer:
Neporo4naja [7]2 years ago
4 0
Calcified tissue. Why: I just know
You might be interested in
how do the properties of compounds compare to the properties of the elements from which they are composed
Crank
<span>The elements that form the compound don't compare because it doesn't matter about the elements when they are combined. The elements that formed it together is completely different than the outcome compound. </span>
6 0
3 years ago
Given the different molecular weights, dipole moments, and molecular shapes, why are their molar volumes nearly the same?
Marina CMI [18]

Answer:

option d

Explanation:

Molecular sizes of gaseous molecules are very less. Volume occupied by the all the molecules of the gases are very less or negligible as compared to the container in which it is kept. Therefore, most of the volume occupied by gaseous molecules are negligible.

Volume occupied by the gaseous molecules are actually the volume of the container and its does not depend upon the amount, molecular mass or dipole moment of the gaseous molecules.

Therefore, the correct option is d ‘Because most of the volume occupied by the substance is empty space.’

8 0
4 years ago
Calculate the standard entropy change for the following reactions at 25°C.
Art [367]

Answer:

(a) ΔSº = 216.10 J/K

(b) ΔSº = - 56.4 J/K

(c) ΔSº = 273.8 J/K

Explanation:

We know the standard entropy change for a given reaction is given by the sum of the entropies of the products minus the entropies of reactants.

First we need to find in an appropiate reference table the standard  molar entropies entropies, and then do the calculations.

(a)        C2H5OH(l)          +        3 O2(g)         ⇒        2 CO2(g)     +    3 H2O(g)

Sº            159.9                          205.2                         213.8                  188.8

(J/Kmol)

ΔSº = [ 2(213.8) + 3(188.8) ]   - [ 159.9  + 3(205.) ]  J/K

ΔSº = 216.10 J/K

(b)         CS2(l)               +         3 O2(g)               ⇒      CO2(g)      +      2 SO2(g)

Sº          151.0                              205.2                         213.8                 248.2

(J/Kmol)

ΔSº  = [ 213.8 + 2(248.2) ] - [ 151.0 + 3(205.2) ] J/K = - 56.4 J/K

(c)        2 C6H6(l)           +        15 O2(g)                     12 CO2(g)     +     6 H2O(g)

Sº           173.3                           205.2                           213.8                    188.8

(J/Kmol)  

ΔSº  = [ 12(213.8) + 6(188.8) ] - [ 2(173.3) + 15( 205.2) ] = 273.8 J/K

Whenever possible we should always verify if our answer makes sense. Note that the signs for the entropy change agree with the change in mol gas. For example in reaction (b) we are going from 4  total mol gas reactants to 3, so the entropy change will be negative.

Note we need to multiply the entropies of each substance by  its coefficient in the balanced chemical equation.

5 0
3 years ago
If a radioactive isotope has a half-life of 26.5 days, how many days does it take for a sample of the isotope to decrease by 35.
dangina [55]

Answer:

16.5 days

Explanation:

Given that:

Half life = 26.5 days

t_{1/2}=\frac {ln\ 2}{k}

Where, k is rate constant

So,  

k=\frac {ln\ 2}{t_{1/2}}

k=\frac {ln\ 2}{26.5}\ days^{-1}

The rate constant, k = 0.02616 days⁻¹

Using integrated rate law for first order kinetics as:

[A_t]=[A_0]e^{-kt}

Where,  

[A_t] is the concentration at time t

[A_0] is the initial concentration

Given:

35.0 % is decomposed which means that 0.35 of [A_0] is decomposed. So,

\frac {[A_t]}{[A_0]} = 1 - 0.35 = 0.65

t = 7.8 min

\frac {[A_t]}{[A_0]}=e^{-k\times t}

0.65=e^{-0.02616\times t}

<u>t = 16.5 days.</u>

7 0
3 years ago
a. How can one tell if a chemical reaction is balanced? (.5 point) b. What information does a complete ionic equation give that
evablogger [386]

Answer:

I think it's C

Explanation:

i think its c b3cause when you guess c always feels right

8 0
2 years ago
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