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4 years ago

How much heat is released if 7.15 g cao(s) is added to 152 g of h2o(l)? cao(s) + h2o(l) → ca(oh)2(s) δh°rxn = –64.8 kj/mol?

1 answer:

6 0

First, we calculate the number of moles of each reactant using the formula:

Moles = mass / molecular weight

CaO:
Moles = 7.15/56 = 0.128

Water:
Moles = 152/18 = 8.44

The reaction equation shows that the reactants must be present in an equal number of moles, so CaO will be the limiting reactant and 0.128 mole of calcium hydroxide will form.

The energy released is given by:

Heat of reaction * number of moles
= -64.8 * 0.128
= -8.29 kJ

8.29 kJ of energy will be released

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A student spends 4.5 hours studying for a test. How much time is this equivalent to in seconds

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3 years ago

A cylinder with a moveable piston contains 0.552 mol of gas and has a volume of 259 mL . Part A What will its volume be if an ad

Naddik [55]

Answer:

The new volume will be 367mL

Explanation:

Using PV = nRT

V1 = 259mL = 0.000259L

n1 = 0.552moles

At constant temperature and pressure, the value is

P * 0.000259 = 0.552 * RT ------equation 1

= 0.552 / 0.000259

= 2131.274

V2 = ?

n2 = 0.552 + 0.232

n2 = 0.784mole

Using ideal gas equation,

PV = nRT

P * V2 = 0.784 * RT ---------- equation 2

Combining equations 1 and 2 we have;

V2 = 0.784 / 2131.274

V2 = 0.000367L

V2 = 367mL

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3 years ago

How many moles of chromium III nitrate are produced When chromium reacts with 0.85 moles of lead for nitrate to produce chromium

Pepsi [2]

0.85 moles formula units of lead nitrate will produce 0.57 moles formula units of chromium (III) nitrate.

<h3>Explanation</h3>

Typically, the oxidation state of Pb in lead nitrate tend to be +2. In other words, Pb in lead nitrate tends to exist as $\text{Pb}^{2+}$ ions. The formula for a nitrate ion is ${\text{NO}_3}^{-}$ . The charge on each of the nitrate ion is -1. The charge on the two ions should balance. As a result, each $\text{Pb}^{2+}$ ion in lead nitrate would pair up with two ${\text{NO}_3}^{-}$ ions. The formula for lead nitrate will be $\text{Pb}({\text{NO}_3})_2$ . Each formula unit of lead nitrate will contain one $\text{Pb}^{2+}$ ion and two ${\text{NO}_3}^{-}$ ions.

The "III" in the name "chromium (III) nitrate" is a Roman Numeral. It indicates that the oxidation state of Cr in chromium (III) nitrate is +3. The Cr in that compound will exist as $\text{Cr}^{3+}$ . Similarly, each $\text{Cr}^{3+}$ will pair up with three ${\text{NO}_3}^{-}$ ions. The formula for chromium (III) nitrate will be $\text{Cr}(\text{NO}_3})_3$ . Each formula unit of chromium (III) nitrate will contain one ${\text{NO}_3}^{-}$ ion and three ${\text{NO}_3}^{-}$ ions.

0.85 moles formula units of lead nitrate will contain 0.85 × 2 = 1.7 moles of ${\text{NO}_3}^{-}$ ions. Those nitrate ions will end up in 1.7 / 3 = 0.57 moles formula units of chromium (III) nitrate. As a result, the reaction will produce 0.57 moles formula units of chromium (III) nitrate.

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4 years ago

What are the three characteristics properties of an acid

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4 years ago

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3 years ago