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Elanso [62]
4 years ago
11

A chemical reaction has a ΔH of -2764 Kj. This indicates that the chemical reaction that took place was

Chemistry
2 answers:
Ket [755]4 years ago
7 0

Answer:

Explanation:

answer was A ENDOTHERMIC

grandymaker [24]4 years ago
4 0
Hello!

The reaction that took place was B) exothermic. 

The equation for the ΔH is 

\Delta H= H products - H reagents

To know if this reaction is exothermic or endothermic we will need to look at the sign of the ΔH. If it is positive, it means that enthalpy of the products is higher than the enthalpy of the reagents and the reaction is endothermic.

If the sign is negative, it means that the enthalpy of the products is lower than the enthalpy of the reagents and the reaction is exothermic. In this case, the sign is negative, so the reaction is exothermic.

Have a nice day!
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Suppose you have 81.8 g of Cd. How many Cd atoms are present? Report your answer in scientific notation using the format of 6.02
Lostsunrise [7]

Answer:

1. number of Cd atoms = 4.384 × 10²³

2. number of moles of Ti = 0.817 mol

3. molar mass of C₇H₆O₃ = 138.077 g/mol

4. moles of Sildenafil = 0.249 mmol

Explanation:

1. given data

mass of Cd = 81.8 g

number of Cd atoms = ?

molar mass of Cd = 112.411 g/mol

Solution

1st we find out the number of moles of Cd

<em>         number of moles = mass / molar mass </em>

 number of moles of Cd = 81.8 g / 112.411 g.mol⁻

 number of moles of Cd = 0.728 mol

Now we find out the number of Cd atoms

<em>       number of atoms = moles × 6.022 × 10²³</em>

 number of Cd atoms = 0.728 (6.022 × 10²³)

 number of Cd atoms = 4.384 × 10²³

 

2. Given data

Mass of Ti = 39.1 g

moles = ?

molar mass Ti = 47.867 g/mol

Solution

Now we will find out the number of moles

<em>         number of moles = mass / molar mass </em>

 number of moles of Ti = 39.1 g / 47.867 g.mol⁻

 number of moles of Ti = 0.817 mol

3. Given data

chemical formula of Salicylic acid  = C₇H₆O₃

molar mass of salicylic acid = ?

molar mass of carbon = 12.011

molar mass of hydrogen = 1.008

molar mass of oxygen = 15.999

<em>         molar mass of  molecule = number of moles of atoms × molar mass of atoms</em>

  molar mass of C₇H₆O₃ = 7 (12.011) + 6 (1) + 3 (16)

  molar mass of C₇H₆O₃ = 84.077 g + 6 g + 48 g

  molar mass of C₇H₆O₃ = 138.077 g/mol

4. Given data

molar mass of Sildenafil = 474.5828 g/mol

mass given = 0.118 g

moles of Sildenafil = ?

Solution

Now we find out the number of moles

<em>          number of moles = mass / molar mass </em>

<em>   </em>number of moles Sildenafil = 0.118 g / 474.5828 g/mol

  number of moles Sildenafil = 0.0003 mol

as this is very small amount we convert it into millimoles

           <em>millimoles = moles × 1000</em>

    millimoles of Sildenafil = 0.000249 × 1000

    millimoles of Sildenafil = 0.249 mmol

4 0
3 years ago
A scientist took notes about the fossil in the picture.
Dimas [21]

Answer:

b. forest ....

I think ansesters also lived in forest by wearing leaves like their clothes .... etc

6 0
3 years ago
Which equation correctly shows an endothermic reaction? *
Nady [450]
It’s A because +1500 kJ is before the arrow. it’s in the reactant side. so it is endothermic.
8 0
3 years ago
The standard molar enthalpy of formation of NH3(g) is -45.9 kJ/mol. What is the enthalpy change if 9.51 g N2(g) and 1.96 g H2(g)
Vladimir [108]

Answer:

\Delta H=-29.7kJ

Explanation:

Hello!

In this case, since the undergoing chemical reaction is:

N_2+3H_2\rightarrow 2NH_3

We first need to identify the limiting reactant given the masses of nitrogen and hydrogen:

n_{NH_3}^{by\ H_2}=1.96gH_2*\frac{1molH_2}{2.02gH_2}*\frac{2molNH_3}{3molH_2}=0.647molNH_3\\\\  n_{NH_3}^{by\ N_2}=9.51gN_2*\frac{1molN_2}{28.02gN_2}*\frac{2molNH_3}{1molN_2}=0.679molNH_3

It means that only 0.647 moles of ammonia are yielded, so the resulting enthalpy change is:

\Delta H=0.647molNH_3*\frac{-45.9kJ}{1molNH_3}\\\\ \Delta H=-29.7kJ

Best regards!

3 0
3 years ago
Rank the compounds NH3, CH4, and PH3 in order of decreasing boiling point. Choices: A) NH3 &gt; CH4 &gt; PH3 B) CH4 &gt; NH3 &gt
Andre45 [30]

Answer:

C) NH3 > PH3 > CH4

Explanation:

The boiling point of a substance depends on the nature of intermolecular interaction between the molecules of the substance. The greater the magnitude of intermolecular interaction between the molecules of the substance, the higher the boiling point of the substance.

Both NH3 and PH3 have intermolecular hydrogen bonding between their molecules. However, since nitrogen is more electronegative than phosphorus, the magnitude of intermolecular hydrogen bonding in NH3 is greater than in PH3 hence NH3 has a higher boiling point than PH3.

CH4 molecules only have weak dispersion forces between them hence they exhibit the lowest boiling point.

7 0
3 years ago
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