Which of the following is always true when a substance undergoes a physical change

You want to determine the concentration of a solid solute dissolved in a specified volume of liquid solvent which of the followi

Natali [406]

Generally, chemists prefer to use morality (B) because it only invovles measuring the final volume of the solution and amount of moles of the solute

Hope this helps

6 0

3 years ago

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Which of the following is NOT a property of a base?

inna [77]

Bases turns cabbage juice yellow or green is not a property of bases.

Explanation:

As per the property of the bases, the correct statements are:

The taste of the bases are bitter.
Solutions of bases are slippery in nature
Bases reacts with the metals to form hydrogen gas and a salt.
For example, sodium hydroxide reacts with zinc metal to form sodium zincate salt and hydrogen gas.

Wrong statement:

It turns cabbage juice yellow or green, whereas it turns the cabbage juice blue or green and acids turns cabbage juice red or pink.

8 0

3 years ago

Why does a metal lawn

jeyben [28]

Answer:

heat travels easier through plants so plants dont heat up as much

thus is because metal is much more dense than the grass

3 0

3 years ago

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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 bond is this combination likely to form

kari74 [83]

Answer:

A combination is certainly possible, but you should not take formal charges so literally

Normally, when a covalent bond is found, the two atoms both bring in one electron. As you identify correctly, in the case of nitric acid that would not be possible completely. If you draw the different possible resonance structures, the most likely structure has a single bond between the nitrogen and an oxygen where the oxygen has 3 lone pairs and both electrons in the bond are donated by the nitrogen. This makes the nitrogen "positive" and that oxygen "negative", but in fact the electrons move more freely in the molecule and charges are more distributed. You will not be able to find "the negatively charged" oxygen atom.

Explanation:

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4 0

3 years ago