(function () {
function textOf(el) {
return (el && el.textContent || "").replace(/\s+/g, " ").trim();
}
function resolveItemUrl() {
var match = window.location.search.match(/[?&]item=(\d+)/);
if (!match) {
return null;
}
return window.location.origin + "/a-" + match[1] + "/";
}
function loadAccordion() {
var url = resolveItemUrl();
if (!url) {
return Promise.resolve(null);
}
return new Promise(function (resolve, reject) {
var xhr = new XMLHttpRequest();
xhr.open("GET", url, true);
xhr.onload = function () {
if (xhr.status < 200 || xhr.status >= 400) {
reject(new Error("item page " + xhr.status));
return;
}
var doc = new DOMParser().parseFromString(xhr.responseText, "text/html");
resolve(doc.querySelector(".phywe-item-accordion"));
};
xhr.onerror = function () {
reject(new Error("item page network error"));
};
xhr.send();
});
}
function parseItemBlocks(scope, withQuantity) {
if (!scope) {
return [];
}
var rows = scope.querySelectorAll(".itemslist .row.itemblocks");
var items = [];
for (var i = 0; i < rows.length; i++) {
var cols = rows[i].children;
if (!cols.length) {
continue;
}
var nameLink = cols[0].querySelector("a");
var numberLink = cols[1] ? cols[1].querySelector("a") : null;
var item = {
name: textOf(nameLink || cols[0]),
mappedTo: textOf(numberLink)
};
if (withQuantity && cols[2]) {
var qty = parseInt(textOf(cols[2]).replace(/[^\d]/g, ""), 10);
item.quantity = isNaN(qty) ? textOf(cols[2]) : String(qty);
}
if (item.name) {
items.push(item);
}
}
return items;
}
function fillTable(tableId, items, withQuantity) {
var table = document.getElementById(tableId);
if (!table || !items.length) {
return;
}
var tbody = table.querySelector("tbody");
for (var i = 0; i < items.length; i++) {
var tr = document.createElement("tr");
var nameTd = document.createElement("td");
nameTd.style.width = "80%";
nameTd.textContent = items[i].name;
tr.appendChild(nameTd);
var numberTd = document.createElement("td");
numberTd.textContent = items[i].mappedTo;
tr.appendChild(numberTd);
if (withQuantity) {
var qtyTd = document.createElement("td");
qtyTd.textContent = items[i].quantity || "";
tr.appendChild(qtyTd);
}
tbody.appendChild(tr);
}
var wrapper = table.parentElement;
while (wrapper && wrapper.className.indexOf("printtablediv") === -1) {
wrapper = wrapper.parentElement;
}
if (wrapper) {
wrapper.style.display = "";
}
}
function stepTitle(stepEl) {
if (!stepEl) {
return "";
}
var titleEl = stepEl.querySelector(".card-header button div") || stepEl.querySelector(".card-header button");
return textOf(titleEl);
}
function setHeadline(tableId, title) {
var headline = document.querySelector("#" + tableId + " .printtableheadline");
if (headline && title) {
headline.textContent = title;
}
}
function parseMedia(scope) {
if (!scope) {
return [];
}
var rows = scope.querySelectorAll(".itemslist .row.itemblocks");
var items = [];
for (var i = 0; i < rows.length; i++) {
var cols = rows[i].children;
if (!cols.length) {
continue;
}
var nameLink = cols[0].querySelector("a");
var fileLink = cols[1] ? cols[1].querySelector("a") : null;
var item = {
name: textOf(nameLink || cols[0]),
mappedTo: textOf(fileLink || cols[1]),
quantity: cols[2] ? textOf(cols[2]) : ""
};
if (item.name) {
items.push(item);
}
}
return items;
}
function fillFromAccordion(accordion) {
if (!accordion) {
return;
}
var versucheStep = accordion.querySelector('[data-step="versuche"]');
var versuche = parseItemBlocks(versucheStep, false);
setHeadline("print-versuche", stepTitle(versucheStep));
fillTable("print-versuche", versuche, false);
var lieferumfangStep = accordion.querySelector('[data-step="lieferumfang"]');
var lieferumfang = parseItemBlocks(lieferumfangStep, true);
fillTable("print-lieferumfang", lieferumfang, true);
var zubehoer = accordion.querySelector('[data-step="zubehoer"]');
var sections = zubehoer ? zubehoer.querySelectorAll(".card-body") : [];
var notwendig = [];
var empfohlen = [];
for (var i = 0; i < sections.length; i++) {
var items = parseItemBlocks(sections[i], false);
if (sections[i].querySelector(".text-red, .icon-warning-black")) {
notwendig = items;
} else if (sections[i].querySelector(".text-green, .icon-Mehrwert_black")) {
empfohlen = items;
}
}
fillTable("print-zubehoer-notwendig", notwendig, false);
fillTable("print-zubehoer-empfohlen", empfohlen, false);
var mediaStep = accordion.querySelector('[data-step="media"]');
var media = parseMedia(mediaStep);
setHeadline("print-media", stepTitle(mediaStep));
fillTable("print-media", media, true);
}
function start() {
var itemUrl = resolveItemUrl();
if (!itemUrl) {
setTimeout(function () {
window.print();
}, 2000);
return;
}
loadAccordion()
.then(function (accordion) {
fillFromAccordion(accordion);
})
.catch(function (err) {
if (window.console && console.warn) {
console.warn("Accordion konnte nicht geladen werden:", resolveItemUrl(), err);
}
})
.then(function () {
setTimeout(function () {
window.print();
}, 500);
});
}
if (document.readyState === "loading") {
document.addEventListener("DOMContentLoaded", start);
} else {
start();
}
})();
Technical data Determining the pKa value of a weak acid with half titrationArticle no: P7511100 ![]()
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
Principle During this experiment, the students have to determine the pKa value of an acetic acid solution with the aid of a suitable indicator (here: phenolphthalein). For this purpose, a known volume of the acid is titrated with a volume of sodium hydroxide of a known concentration (standard solution) until the indicator changes colour. The used volume of the standard solution is read off the burette. The used amount is divided by two. The calculated amount is then added as acetic acid to the original vessel and the solution is tested with a pH strip. The determined pH value is equal to the pKa value of the acetic acid. Learning objectives
Benefits
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Robert-Bosch-Breite 10 – 37079 Göttingen – Germany
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Robert-Bosch-Breite 10 – 37079 Göttingen – Germany
www.phywe.com


