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3 years ago

I’m very confused on how to solve this

Chemistry

1 answer:

Bond [772]3 years ago

4 0

Recall that density is Mass/Volume. We are given the mL of liquid which is volume so all we need is mass now. We are given the mass of the granulated cylinder both with and without the liquid, so if we subtract them, we can get the mass of the liquid by itself. So, 136.08-105.56= 30.52g. This is the mass of the liquid. We now have all we need to find the density. So, let’s plug these into the density formula. 30.52g/45.4mL= 0.672 g/mL. This is our final answer since the problem requests the answer in g/mL, but be careful, because some problems in the future may ask for g/L requiring unit conversions. Also note that 30.52 was 4 sigfigs and 45.4 was 3 sigfigs, and so dividing them required an answer that was 3 sigfigs as well, hence why the answer is in the thousandths place

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During lab, a student used a Mohr pipet to add the following solutions into a 25 mL volumetric flask. They calculated the final

kompoz [17]

Answer:

(FeSCN⁺²) = 0.11 mM

Explanation:

Fe ( NO3)3 (aq) [0.200M] + KSCN (aq) [ 0.002M] ⇒ FeSCN+2

M (Fe(NO₃)₃ = 0.200 M

V (Fe(NO₃)₃ = 10.63 mL

n (Fe(NO₃)₃ = 0.200*10.63 = 2.126 mmol

M (KSCN) = 0.00200 M

V (KSCN) = 1.42 mL

n (KSCN) = 0.00200 * 1.42 = 0.00284 mmol

Total volume = V (Fe(NO₃)₃ + V (KSCN)

= 10.63 + 1.42

= 12.05 mL

Limiting reactant = KSCN

So,

FeSCN⁺² = 0.00284 mmol

M (FeSCN⁺²) = 0.00284/12.05

= 0.000236 M

Excess reactant = (Fe(NO₃)₃

n(Fe(NO₃)₃ = 2.126 mmol - 0.00284 mmol

=2.123 mmol

For standard 2:

n (FeSCN⁺²) = 0.000236 * 4.63

=0.00109

V(standard 2) = 4.63 + 5.17

= 9.8 mL

M (FeSCN⁺²) = 0.00109/9.8

= 0.000111 M = 0.11 mM

Therefore, (FeSCN⁺²) = 0.11 mM

7 0

3 years ago

6. The pOH of a solution of NaOH is 11.30. What is the [H+ ] for this solution?

sashaice [31]

Answer:

The [H⁺] for this soluton is 2*10⁻³ M

Explanation:

pH, short for Hydrogen Potential and pOH, or OH potential, are parameters used to measure the degree of acidity or alkalinity of substances.

The values that compose them vary from 0 to 14 and the pH value can be directly related to that of pOH by means of:

pH + pOH= 14

In this case, pOH=11.30, so

pH + 11.30= 14

Solving:

pH= 14 - 11.30

pH= 2.7

Mathematically the pH is the negative logarithm of the molar concentration of the hydrogen or proton ions (H⁺) or hydronium ions (H₃O):

´pH= - log [H⁺] = -log [H₃O]

Being pH=2.7:

2.7= - log [H⁺]

[H⁺]= 10⁻² ⁷

[H⁺]=1.995*10⁻³ M≅ 2*10⁻³ M

The [H⁺] for this soluton is 2*10⁻³ M

8 0

4 years ago

What type of reaction occurs initially with sodium azide when airbags initially deploy.

Luden [163]

The chemical at the heart of the air bag reaction is called sodium azide, or NaN3. CRASHES trip sensors in cars that send an electric signal to an ignitor. The heat generated causes sodium azide to decompose into sodium metal and nitrogen gas, which inflates the car's air bags.

8 0

3 years ago

A decorative "ice" sculpture is carved from dry ice (solid CO2) and held at its sublimation point of –78.5°C. Consider the proce

Leno4ka [110]

Answer:

The answers to the questions are;

a. The entropy of sublimation for carbon dioxide (the system) is

134.07 J/Kmol.

b. The entropy of the universe for this reversible process is 376 J/K.

Explanation:

Entropy of sublimation is the entropy change experienced following the transformation of a mole of solid to vapor at the temperature where the sublimation is taking place

a. We note that the mass of the solid CO₂ = 389 g

Molar mass of CO₂ = 44.01 g/mol

Number of moles of CO₂ in the sculpture = Mass/(Molar mass)

= (389 g)/(44.01 g/mol) = 8.84 Moles

Entropy of sublimation is given by

ΔS $_{sublimation}$ = $S_{vapor}$ - S $_{solid}$ = $\frac{\Delta H_{sublimation}}{T}$