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3 years ago

Please i need the answer im dying here ;-

Chemistry

2 answers:

ELEN [110]3 years ago

8 0

Answer:

anawer is none of the above

Serggg [28]3 years ago

7 0

Answer:

i think none of the above is the answer

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The atomic number of an element is determined by the number of electrons in the nucleus of the atom.

iren [92.7K]

A
The number of electrons/protons is the one that determines the atomic number of an element.

7 0

3 years ago

Read 2 more answers

: How much energy is required to heat an iron nail with a mass of 25.5 grams from 65°C until it becomes red hot at 720°C?

Evgen [1.6K]

Q = mct

-Q= energy in Joules

-m = mass in grams

-c= specific heat capacity in J/g degree C

-t = delta temperature in degrees Celsius

So,

Q = m c t

Q = (7 grams)(0.448J/g C)(750 C - 25 C)

Q = 2273.6 J

Your final answer = 2273.6 Joules

8 0

3 years ago

The following reaction does not proceed to a product: H2O + Cu --> no reaction. Why is that?

Anettt [7]

I think the correct answer would be because copper has a lower activity than hydrogen and cannot replace the bonds in it. Substances that are not oxidizing do not react with copper since the redox potentials are very low. Hope this answers the question.

5 0

3 years ago

Read 2 more answers

7.00 of Compound x with molecular formula C3H4 are burned in a constant-pressure calorimeter containing 35.00kg of water at 25c.

beks73 [17]

Answer:

$\Delta H_{f,C_3H_4}=276.8kJ/mol$

Explanation:

Hello!

In this case, since the equation we use to model the heat exchange into the calorimeter and compute the heat of reaction is:

$\Delta H_{rxn} =- m_wC_w\Delta T$

We plug in the mass of water, temperature change and specific heat to obtain:

$\Delta H_{rxn} =- (35000g)(4.184\frac{J}{g\°C} )(2.316\°C)\\\\\Delta H_{rxn}=-339.16kJ$

Now, this enthalpy of reaction corresponds to the combustion of propyne:

$C_3H_4+4O_2\rightarrow 3CO_2+2H_2O$

Whose enthalpy change involves the enthalpies of formation of propyne, carbon dioxide and water, considering that of propyne is the target:

$\Delta H_{rxn}=3\Delta H_{f,CO_2}+2\Delta H_{f,H_2O}-\Delta H_{f,C_3H_4}$

However, the enthalpy of reaction should be expressed in kJ per moles of C3H4, so we divide by the appropriate moles in 7.00 g of this compound:

$\Delta H_{rxn} =-339.16kJ*\frac{1}{7.00g}*\frac{40.06g}{1mol}=-1940.9kJ/mol$

Now, we solve for the enthalpy of formation of C3H4 as shown below:

$\Delta H_{f,C_3H_4}=3\Delta H_{f,CO_2}+2\Delta H_{f,H_2O}-\Delta H_{rxn}$

So we plug in to obtain (enthalpies of formation of CO2 and H2O are found on NIST data base):

$\Delta H_{f,C_3H_4}=3(-393.5kJ/mol)+2(-241.8kJ/mol)-(-1940.9kJ/mol)\\\\\Delta H_{f,C_3H_4}=276.8kJ/mol$

Best regards!

7 0

2 years ago

What type of reaction is most likely to occur when barium reacts with fluorine? write the chemical equation for the reaction?

scZoUnD [109]

Answer is: this is synthesis reaction.<span>
</span>Chemical reaction: Ba + F₂ → BaF₂.
Synthesis reaction<span> is a type of reaction in which multiple reactants combine to form a single product.
</span>In barium fluoride, barium has oxidation number +2 and fluorine has oxidation number -1, so compound has neutral charge.

6 0

2 years ago