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3 years ago

Which of the following is NOT a symbol for an element? H Li Pb HF

Chemistry

2 answers:

sp2606 [1]3 years ago

3 0

HF because an element is always a capital then a lowercase letter

ohaa [14]3 years ago

3 0

HF because an element always has a capital letter first then a lowercase.

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A gas occupies 56 L at 73°C. What volume will the gas occupy if the temp. cools to 0°C?

vova2212 [387]

Answer:

44.2 L

Explanation:

Use Charles Law:

$\frac{V1}{T1} =\frac{V2}{T2}$

We have all the values except for V₂; this is what we're solving for. Input the values:

$\frac{56 L}{346K} =\frac{V2}{273K}$ - make sure that your temperature is in Kelvin

From here, we need to get V₂ by itself. To do this, multiply by 273 on both sides:

$\frac{56*273}{346} = V2$

Therefore, V₂ = 44.2 L

It's also helpful to know that temperature and volume are linearly related. So, when temperature drops, so will volume and vice versa.

7 0

2 years ago

Given the balanced equation what is the reaction ?

VMariaS [17]

This is a double replacement reaction; the ions switch twice.

3 0

3 years ago

Which part of the body contains enzymes that break down protein? A. Skin B. Brain C. Stomach D. Teeth

kiruha [24]

either c or d but more likely d because food is mainly broken down in your stomach

8 0

3 years ago

Read 2 more answers

calculate the heat required in joules to convert 18.0 grams of water ice at a temperature of -20 c to liquid water at the normal

KIM [24]

Answer:

Explanation:

Heat required to convert ice to ice at 0⁰C

= mass x specific heat x rise in temperature

= 18 x 2.09 x 20

= 752.4 J .

heat required to convert ice at 0⁰C to water at 0⁰C

mass x latent heat of fusion

= 18 x 336

= 6048 J

Heat required to increase the temperature of water to 100⁰C

= 18 x 4.2 x 100

= 7560 J

Total heat required

7560 + 6048 + 752.4

= 14360.4 J

7 0

2 years ago

Measurements show that unknown compound has the following composition: element mass 38.7 % calcium, 19.9 % phosphorus and 41.2 %

Mademuasel [1]

Answer:

D) empirical formula is: C₃P₂O₈

Explanation:

Given:

Mass % Calcium (Ca) = 38.7%

Mass % Phosphorus (P) = 19.9%

Mass % oxygen (O) = 41.2 %

This implies that for a 100 g sample of the unknown compound:

Mass Ca = 38.7 g

Mass P = 19.9 g

Mass O = 41.2 g

Step 1: Calculate the moles of Ca, P, O

Atomic mass Ca = 40.08 g/mol

Atomic mass P = 30.97 g/mol

Atomic mass O = 16.00 g/mol

$Moles\ Ca = \frac{38.7g}{40.08g/mol} =0.966\ mol\\\\Moles\ P = \frac{19.9g}{30.97g/mol} =0.643\ mol\\\\Moles\ O = \frac{41.2g}{16.00g/mol} =2.58\ mol$

Step 2: Calculate the molar ratio

$C = \frac{0.966}{0.643} =1.50\\\\P = \frac{0.643}{0.643} = 1.00\\\\O = \frac{2.58}{0.643} =4.00$

Step 3: Calculate the closest whole number ratio

C: P: O = 1.50 : 1.00 : 4.00

C : P : O = 3:2:8

Therefore, the empirical formula is: C₃P₂O₈

7 0

3 years ago