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Makovka662 [10]

3 years ago

9

there are tiny plants growing on rock fence after the several year . you observe something happened on the rock which of the fol

lowing describes your observations ? the plants the rock

1 answer:

Bingel [31]3 years ago

5 0

it is moss

Explanation:

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The formula in my book for carbonate is Co32- and I’m confused because carbon has 4 valence electrons and oxygen has 6 . How doe

balandron [24]

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4 0

3 years ago

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Exchanging ideas about science is called ______?

sesenic [268]

Communication.

When people exchange ideas about science, they are communicating with one another to both share and obtain knowledge. Collaboration is a large part of this communication, as the exchange of these ideas often leads to new discoveries and inventions.

5 0

3 years ago

The combined gas law states that

seropon [69]

Answer:

Option B. PV = nRT.

Explanation:

From the above,

C = PV / T. (1)

But, C is directly proportional to n, where R is the gas constant i.e

C & n

C = nR

Substituting the value of C into equation (1), we have:

C = PV / T

nR = PV / T

Cross multiply to express in linear form

nRT = PV

Therefore,

PV = nRT

8 0

3 years ago

What is the difference between gamma radiation and x-ray radiation?

kicyunya [14]

X-ray radiation can be deadly but its only deadly in large amounts when you get an x-ray it is only for a picture. Gamma radiation is the most harmful radiation as it penetrates everything and gives off deadly radiation and it isn't very common.

3 0

4 years ago

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A student dissolves 15.0 g of ammonium chloride(NH4Cl) in 250. 0 g of water in a well-insulated open cup. She then observes the

iren2701 [21]

Answer:

1) Endothermic.

2) $Q_{rxn}=4435.04J$

3) $\Delta _rH=15.8kJ/mol$

Explanation:

Hello there!

1) In this case, for these calorimetry problems, we can realize that since the temperature decreases the reaction is endothermic because it is absorbing heat from the solution, that is why the temperature goes from 22.00 °C to 16.0°C.

2) Now, for the total heat released by the reaction, we first need to assume that all of it is released by the solution since it is possible to assume that the calorimeter is perfectly isolated. In such a way, it is also valid to assume that the specific heat of the solution is 4.184 J/(g°C) as it is mostly water, therefore, the heat released by the reaction is:

$Q_{rxn}=-(15.0g+250.0g)*4.184\frac{J}{g\°C}(16.0-20.0)\°C\\\\ Q_{rxn}=4435.04J$

3) Finally, since the enthalpy of reaction is calculated by dividing the heat released by the reaction over the moles of the solute, in this case NH4Cl, we proceed as follows:

$\Delta _rH=\frac{ Q_{rxn}}{n}\\\\\Delta _rH= \frac{ 4435.04J}{15.0g*\frac{1mol}{53.49g} } *\frac{1kJ}{1000J} \\\\\Delta _rH=15.8kJ/mol$

Best regards!

Best regards!

4 0

3 years ago