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3 years ago

Check the approach to obtain the correct conversion equation. Use the temperature in °F to find the temperature in °C.

Chemistry

1 answer:

Maru [420]3 years ago

8 0

Answer:

( °F − 32) × 5/9 = °C

Explanation:

Also there is a mental calculation to convert from Fahrenheit to Celsius. The ratio 5/9 is approximately equal 0.55555….

Subtract 32º to adapt the equivalent in the Fahrenheit scale.

Divide the degrees Celsius by 2 (multiply by 0.5).

Take 1/10 of this number (0.5 * 1/10 = 0.05) and add it to the number obtained previously.

Example: Convert 98.6º F to Centigrade.

98.6 - 32 = 66.6

66.6 * 1/2 = 33.3

33.3 * 1/10 = 3.3

33.3 + 3.3 = 36.6 which is an approximation in degrees Centigrade

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3 years ago

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Cerrena [4.2K]

Answer:

Boyle's Law

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3 years ago

A 200.0 mL solution of 0.40 M ammonium chloride was titrated with 0.80 M sodium hydroxide. What was the pH of the solution after

choli [55]

Answer:

9.25

Explanation:

Let first find the moles of $NH_4Cl$ and $NaOH$

number of moles of $NH_4Cl$ = 0.40 mol/L × 200 × 10⁻³L

= 0.08 mole

number of moles of $NaOH$ = 0.80 mol/L × 50 × 10⁻³L

= 0.04 mole

The equation for the reaction is expressed as:

$NH^+_{4(aq)} \ + OH^-_{(aq)} ------> NH_{3(g)} \ + H_2O_{(l)}$

The ICE Table is shown below as follows:

$NH^+_{4(aq)} \ + OH^-_{(aq)} ------> NH_{3(g)} \ + H_2O_{(l)}$

Initial (M) 0.08 0.04 0

Change (M) - 0.04 -0.04 + 0.04

Equilibrium (M) 0.04 0 0.04

$K_a*K_b = 10^{-14} \ at \ 25^0C$

$K_a = \frac{10^{-14}}{K_b}$

$K_a = \frac{10^{-14}}{1.76*10^{-5}}$

$K_a= 5.68*10^{10}$

$pK_a = - log \ (K_a)$

$pK_a = - log \ (5.68*10^{-10})$

$pK_a = 9.25$

$pH = pKa + \ log (\frac{HB}{HA} )$ for buffer solutions

$pH = pKa + \ log (\frac{moles \ of \ base }{ moles\ of \ acid} )$ since they are in the same solution

$pH = 9.25 + \ log (\frac{0.04 }{ 0.04} )$

$pH = 9.25$

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3 years ago

What is the pressure in millimeters of mercury of 0.0130 molmol of helium gas with a volume of 210. mLmL at 55 ∘C∘C? (Hint: You

juin [17]

Answer : The pressure of the helium gas is, 1269.2 mmHg

Explanation :

To calculate the pressure of the gas we are using ideal gas equation:

$PV=nRT$

where,

P = Pressure of $He$ gas = ?

V = Volume of $He$ gas = 210. mL = 0.210 L (1 L = 1000 mL)

n = number of moles $He$ = 0.0130 mole

R = Gas constant = $0.0821L.atm/mol.K$

T = Temperature of $He$ gas = $55^oC=273+55=328K$

Putting values in above equation, we get:

$P\times 0.210L=0.0130mole\times (0.0821L.atm/mol.K)\times 328K$

$P=1.67atm=1269.2mmHg$

Conversion used : (1 atm = 760 mmHg)

Thus, the pressure of the helium gas is, 1269.2 mmHg

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3 years ago

(h) The student made observations related to the contents of the Erlenmeyer flask during the titration. Identify an observation

katen-ka-za [31]

Answer:

Explanation:

During titration indicators are often used to identify chemical changes between reacting species.

For colorless solutions in which no noticeable changes can easily be seen, indicators are the best bet. Most titration processes involves a combination of acids and bases to an end point.

Indicators are substances whose color changes to signal the end of an acid-base reaction. Examples are methyl orange, methyl red, phenolphthalein, litmus, cresol red, cresol green, alizarin R3, bromothymol blue and congo red.

Most of these indicators have various colors when chemical changes occur.

Also, there are heat changes that accompanies most of these reactions. These are also indicators of chemical changes.

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3 years ago