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2 years ago

Explain why seeing a gas doesn not always indicate that there was a chemical change.

Chemistry

1 answer:

Orlov [11]2 years ago

7 0

A change of state (which is a physical change) can cause gas.

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A solution is made by dissolving 4.87 g of potassium nitrate in water to a final volume of 86.4 mL solution. What is the weight/

lara31 [8.8K]

Answer:

A solution is made by dissolving 4.87 g of potassium nitrate in water to a final volume of 86.4 mL solution. The weight/weight % or percent by mass of the solute is :

2.67%

Explanation:

Note : Look at the density of potassium nitrate in water if given in the question.

You are calculating weight /Volume not weight/weight % or percent by mass of the solute

Here the weight/weight % or percent by mass of the solute is asked : So first convert the VOLUME OF SOLUTION into MASS

Density of potassium nitrate in water KNO3 = 2.11 g/mL

$density=\frac{mass}{volume}$

Density = 2.11 g/mL

Volume of solution = 86.4 mL

$2.11=\frac{mass}{86.4}$

$mass = 2.11\times 86.4$

$mass=182.3grams$

Mass of Solute = 4.87 g

Mass of Solution = 183.2 g

w/w% of the solute =

$= \frac{mass\ of\ solute}{mass\ of\ solution}\times 100$

$=\frac{4.87}{183.2}\times 100$

w/w%=2.67%

8 0

3 years ago

What is the Bronsted acid of H2PO4- + OH-. ---- HPO42- + H2O?

RoseWind [281]

Answer:

The bronsted- Lowry acid is H₂PO₄⁻

Explanation:

Bronsted-Lowry acid donates a proton (H⁺)

H₂PO₄⁻ + OH⁻ → HPO₄²⁻ + H₂O

In the reaction above, H₂PO₄⁻ is donating the proton to OH⁻ resulting in H₂O and the deprotonated species. This makes it a bronsted-Lowry acid.

7 0

2 years ago

Read 2 more answers

A 1.24g sample of a hydrocarbon, when completely burned in an excess of O2 yields 4.04g Co2 and 1.24g H20. Draw plausible struct

arsen [322]

Answer:

Plausible structure has been given below

Explanation:

Molar mass of $CO_{2}$ is 44 g/mol and molar mass of $H_{2}O$ is 18 g/mol
Number of mole = (mass/molar mass)

4.04 g of $CO_{2}$ = $\frac{4.04}{44}moles$ $CO_{2}$ = 0.0918 moles of $CO_{2}$

1 mol of $CO_{2}$ contains 1 mol of C atom

So, 0.0918 moles of $CO_{2}$ contains 0.0918 moles of C atom

1.24 g of $H_{2}O$ = $\frac{1.24}{18}moles$ $H_{2}O$ = 0.0689 moles of $H_{2}O$

1 mol of $H_{2}O$ contain 2 moles of H atom

So, 0.0689 moles of $H_{2}O$ contain $(2\times 0.0689)moles$ of $H_{2}O$ or 0.138 moles of $H_{2}O$

Moles of C : moles of H = 0.0918 : 0.138 = 2 : 3

Empirical formula of hydrocarbon is $C_{2}H_{3}$

So, molecular formula of one of it's analog is $C_{4}H_{6}$

Plausible structure of $C_{4}H_{6}$ has been given below.

4 0

2 years ago

It has been proven that North America is moving west about 2 cm per year. How many kilometers wouldn’t move in 5000 years

Viefleur [7K]

0.1 km

2cm/year * 5000 yrs = 10000 cm

1cm= .01 m

1km = 1000 m

so the answer is 0.1 km

7 0

3 years ago

What is the percent yield of NaCl if 31g of CuCl2 reacts with excess NaNo3 to produce 21.2g of NaCl

Valentin [98]

The answer is 78.7% yield.

3 0

3 years ago

Explain why seeing a gas doesn not always indicate that there was a chemical change. ​

Explain why seeing a gas doesn not always indicate that there was a chemical change.