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3 years ago

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What is the sign of the heat change for an exothermic reaction? for an endothermic reaction?

1 answer:

Julli [10]3 years ago

3 0

A system that releases heat to the surroundings, an exothermic reaction, has a negative ΔH by convention, because the enthalpy of the products is lower than the enthalpy of the reactants of the system. The enthalpies of these reactions are less than zero, and are therefore exothermic reactions

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How many grams of aluminum chloride must decompose to produce 78.3 milliliters of aluminum metal, if the density of aluminum is

Vilka [71]

1mol aluminium chloride gives 1mol aluminium and 3mol chloride
density equals mass divided by volume
d=m/v
m=v*d
=78.3*2.7
=211.41grams

7 0

4 years ago

Which of the following is an example of behavioral variation?

ANTONII [103]

Answer: A, parrots eat seeds, fruit, and nuts, while hawks eat meat.

Explanation:

This option is more onto the behavioral and what the parrots did, while the other options were more on the parrots physical attributions.

<em>I hope this helped! :)</em>

5 0

4 years ago

Under certain conditions Argon gas diffuses at a rate of 3.2 cm per second under the same conditions an unknown gas diffuses at

kozerog [31]

Answer:

20 g/mol

Explanation:

We can use <em>Graham’s Law of diffusion</em>:

The rate of diffusion (<em>r</em>) of a gas is inversely proportional to the square root of its molar mass (<em>M</em>).

$r = \frac{1 }{\sqrt{M}}$

If you have two gases, the ratio of their rates of diffusion is

$\frac{r_{2}}{r_{1}} = \sqrt{\frac{M_{1}}{M_{2}}}$

Squaring both sides, we get

$(\frac{r_{2}}{r_{1}})^{2} = \frac{M_{1}}{M_{2}}$

Solve for <em>M</em>₂:

$M_{2} = M_{1} \times (\frac{r_{1}}{r_{2}})^{2}$

$M_{2} = \text{39.95 g/mol} \times (\frac{\text{3.2 cm/s}}{\text{4.5 cm/s}})^{2}= \text{39.95 g/mol} \times (0.711 )^{2}$

$= \text{39.95 g/mol} \times 0.506 = \textbf{20 g/mol}$

7 0

3 years ago

The spectrophotometer really measures the percent of light that is transmitted through the solution. The instrument then convert

Fantom [35]

Hey there!:

absorbance = log 100 - log Transmitance

absorbace = 0.85

log 100 = 2

- log transmitance = absorbace / log 100

0.85 / 2= 0.425

transmitance = 10 ^ ( - 0.425 )

transmitance = 0.376

4 0

3 years ago

How long would it take the same amount of gaseous i2 to effuse from the same container under identical conditions?

77julia77 [94]

(46 sec) x √ ((253.80894 g I2/mol) / (44.0128 g N2O/mol)) = 110 sec

7 0

3 years ago