All categories

3 years ago

PLEASE HELP

2 answers:

8 0

Sample response: Susana's red crystal sample is a compound because it was broken down into a gas and blue powder. It is not an element because elements cannot be broken down into simpler substances by ordinary means, such as heating.

This is late but if anyone needs it here you go.

svp [43]3 years ago

7 0

Because more than one substance was released (following a color change signifying a chemical reaction), the sample was indeed, a compound.

You might be interested in

Question 2: Which of the following is NOT true about streams?

mafiozo [28]

Answer:

q 3 c q 2 d

Explanation:

8 0

3 years ago

What is the only true way to tell if a chemical reaction has occurred? CFU

Murljashka [212]

Answer:

change of colour

Explanation:

3 0

4 years ago

Give the charge and full ground-state electron configuration of the monatomic ion most likely to be formed by the element. rb

devlian [24]

Actually Rb or Rubidium in zero state has the following electron configuration:

1s22s22p63s23p63d104s24p65s1

However we can see that the ion has a 1 positive charge, which means that it lacks 1 electron, therefore the answer from the choices is:

d. rb+: 1s22s22p63s23p64s23d104p6

3 0

3 years ago

Three kilograms of steam is contained in a horizontal, frictionless piston and the cylinder is heated at a constant pressure of

lakkis [162]

Answer:

Final temperature: 659.8ºC

Expansion work: 3*75=225 kJ

Internal energy change: 275 kJ

Explanation:

First, considering both initial and final states, write the energy balance:

$U_{2}-U_{1}=Q-W$

Q is the only variable known. To determine the work, it is possible to consider the reversible process; the work done on a expansion reversible process may be calculated as:

$dw=Pdv$

The pressure is constant, so: $w=P(v_{2}-v_{1} )=0.5*100*1.5=75\frac{kJ}{kg}$ (There is a multiplication by 100 due to the conversion of bar to kPa)

So, the internal energy change may be calculated from the energy balance (don't forget to multiply by the mass):

$U_{2}-U_{1}=500-(3*75)=275kJ$

On the other hand, due to the low pressure the ideal gas law may be appropriate. The ideal gas law is written for both states:

$P_{1}V_{1}=nRT_{1}$

$P_{2}V_{2}=nRT_{2}\\V_{2}=2.5V_{1}\\P_{2}=P_{1}\\2.5P_{1}V_{1}=nRT_{2}$

Subtracting the first from the second:

$1.5P_{1}V_{1}=nR(T_{2}-T_{1})$

Isolating $T_{2}$ :

$T_{2}=T_{1}+\frac{1.5P_{1}V_{1}}{nR}$

Assuming that it is water steam, n=0.1666 kmol

$V_{1}=\frac{nRT_{1}}{P_{1}}=\frac{8.314*0.1666*373.15}{500} =1.034m^{3}$

$T_{2}=100+\frac{1.5*500*1.034}{0.1666*8.314}=659.76$ ºC

7 0

3 years ago

Cycloheptatrienone is stable, but cyclopentadienone is so reactive that it can't be isolated. Taking into account the polarity o

Lorico [155]

Answer and Explanation:

The resonance contributor in cyclopentadienone (as shown in the attachment below) results into the compound having a positive charge on the carbonyl group, C=O which accounts for a highly reactive anti-aromatic 4π system. And this illustrates the reason for its instability.

3 0

3 years ago