What is the correct formula for sulfuric acid

What is the result of the following calculation? Record to the correct number of significant figures. 7.94 g + 0.0132 g = ?

Korolek [52]

I think........ a. 7.95

3 0

2 years ago

Write a balanced equation for the combustion of C7H16(l) (heptane) -- i.e. its reaction with O2(g) forming the products CO2(g) a

JulsSmile [24]

Answer:

The standard enthalpy of reaction = -4854.7kJ

The difference: ΔH-ΔE = Δ(PV) = Δn.R.T = 9910.288 J ≈ 9.91 kJ

Explanation:

The balanced chemical equation for the combustion of heptane:

C₇H₁₆ (l) + 11 O₂ (g) → 7 CO₂ (g) + 8 H₂O (l)

Given: The standard enthalpy of formation ( $\Delta H _{f}^{\circ }$ ) for: C₇H₁₆ (l) = -187.8 kJ/mol, O₂ (g) = 0 kJ/mol, CO₂ (g) = -393.5 kJ/mol, H₂O (l) = -286 kJ/mol

To calculate the standard enthalpy of reaction ( $\Delta H _{r}^{\circ }$ ) can be calculated by the Hess's law:

$\Delta H _{r}^{\circ } = \left [\sum \nu \cdot\Delta H _{f}^{\circ }(products) \right ] - \left [\sum \nu\cdot\Delta H _{f}^{\circ }(reactants) \right ]$

Here, $\nu$ is the stoichiometric coefficient

⇒ $\Delta H _{r}^{\circ } =$

$\left [ 7\times \Delta H _{f}^{\circ }\left (CO_{2}\right )+ 8\times \Delta H _{f}^{\circ }\left (H_{2}O \right )\right ]$

$- \left [1\times \Delta H _{f}^{\circ }\left (C_{7}H_{16}\right ) +11\times \Delta H _{f}^{\circ }\left (O_{2} \right ) \right ]$

$=\left [ 7\times \left (-393.5 kJ/mol \right )+ 8\times \left (-286 kJ/mol \right )\right ]$

$-\left [1\times \left (-187.8 kJ/mol \right ) +11\times \left (0 kJ/mol \right ) \right ]$

⇒ $\Delta H _{r}^{\circ } = \left [ \left (-2754.5 \right )+ \left (-2288 \right )\right ]\left -[ \left (-187.8 \right ) +\left (0 \right )\right ]$

⇒ $\Delta H _{r}^{\circ } = \left [ -5042.5 ]\left -[ -187.8] = \left ( -4854.7kJ \right )$

To calculate the difference: ΔH-ΔE=Δ(PV)

We use the ideal gas equation: P.V = n.R.T

⇒ ΔH-ΔE=Δ(PV) = Δn.R.T

Given: Temperature:T = 298K, R = 8.314 J⋅K⁻¹⋅mol⁻¹

Δn = number of moles of gaseous products - number of moles of gaseous reactants = (7)- (11) = (-4)

⇒ ΔH-ΔE=Δ(PV) = Δn.R.T = (-4 mol) × (8.314 J⋅K⁻¹⋅mol⁻¹) × (298K) = 9910.288 J = 9.91 kJ (∵ 1 kJ = 1000J )

8 0

2 years ago

A gas with a volume of 4.0 L at 90.0 kPa expands until the pressure drops to 20.0 kPa. What is its new volume if the temperature

Flauer [41]

You are trying to find V2, the formula is V2= P1 / P2 ⋅ V1
input your numbers, V2= 90.0kPa / 20.0kPa ⋅ 4.0 L to get 18 L

4 0

2 years ago

A geochemist measures the concentration of salt dissolved in Lake Parsons, an isolated salt lake. He finds a concentration of 21

VikaD [51]

Answer:

68,2%

Explanation:

Supposing the initial salt concentration of lake Parsons is the same of non-isolated lakes, 6,67L, and the change of salt concentration in isolated lake is just for water evaporation it is possible to write:

6,67gL⁻¹×X = 21gL⁻¹×Y

-Where X is the initial water and Y is the water that remains in the isolated lake-

Thus:

6,67X = 21Y

0,318 = Y/X

0,318 is the ratio of water that remains between total water. To obtain the ratio of evaporated water:

1-0,318 = 0,682

In percentage: 68,2%

I hope it helps!

3 0

3 years ago

7. What type of water pollution is produced from chemicals used to kill bugs and weeds?

Serga [27]

Answer:

Groundwater pollution

Explanation:

Pesticides, when sprayed on crop plants, are able to flow below the surface of the ground, reaching water-bearing aquifers, thereby contaminating groundwater, making it unsuitable for both human and agricultural uses.

5 0

2 years ago